SEARCH · PubMed Health

Results for “Propensity Score”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources

PubMed2001

Impact of complementary oral enzyme application on the postoperative treatment results of breast cancer patients--results of an epidemiological multicentre retrolective cohort study.

PURPOSE: [corrected] To evaluate the impact of postoperative treatment with an oral enzyme (OE) preparation given complementary to an antineoplastic therapy in patients with breast cancer. METHODS: The design of this epidemiological study was a retrolective cohort analysis with parallel groups. Design and conduct of the study were performed to current standards for prospective, controlled clinical trials. A cohort of 2,339 breast cancer patients undergoing surgical intervention and radio-, chemo- or hormonal therapy were studied in 216 centres. Of the 2,339 patients, 1,283 received complementary treatment with OE and 1,056 did not receive OE. Patients with other complementary medications were excluded and the final analysis was performed with the data from 649 patients, of whom 239 (37%) were additionally treated with OE (test group) and 410 (63%) without OE (control group). The median follow-up time for the test group was 485 days and for the control group 213 days. The primary endpoint of the study was to determine whether complementary treatment with OE can reduce typical disease- or therapy-associated signs and symptoms (gastrointestinal symptoms, mental symptoms, dyspnoea, headache, tumour pain, cachexia, skin disorders, infections, and side effects associated with the antineoplastic therapy) in patients with breast cancer. Imbalances for causal effects (covariates) were adjusted for by means of the propensity score. Outcome analysis was performed by estimating the linear regression between change in symptom score and propensity score with all data and using this regression line to calculate the change in symptom score which would be expected for each patient. Tumour-associated events (recurrence, metastasis, and death) were evaluated in terms of the number of events observed and time to event. The safety of treatment with OE was analysed in terms of the number and severity of adverse events, their duration, treatment and outcome. RESULTS: For all symptoms except tumour pain, the adjusted mean improvement in symptom scores was larger in the test group than in the control group. The adjusted difference was statistically significant for all symptoms, except tumour pain and infections. The results show that the typical disease- and therapy-associated signs and symptoms in patients on complementary therapy with OE during postoperative treatment were significantly less. For 75% of the test group and 55% of the control group the physician recorded "no signs and symptoms". A clear reduction in the side effects of radiotherapy and chemotherapy was documented in 74% of the test group and 55% of the control group. Analysis of survival, recurrence, and metastasis demonstrated a reduced number of events in the test group. There was evidence of a beneficial influence of OE on time to event, although the median observation time was too short in these breast cancer patients to draw definite conclusions. The safety component was judged in 98% of the test group and 76% of the control group as "very good" or "good". In the total sample of 2,339 patients, the rate of OE-associated adverse reactions was 3.2%. All side effects were mild to moderate gastrointestinal symptoms. CONCLUSION: Complementary treatment of breast cancer patients with OE improves the quality of life by reducing signs and symptoms of the disease and the side effects of adjuvant antineoplastic therapies. This epidemiological retrolective cohort analysis provides evidence that the patients may also gain benefit by a prolongation of the time to event for cancer recurrence, metastasis and survival. OE was generally well tolerated.

Adolescent↗

PubMedDate not supplied

Influence of postoperative complementary treatment with lectin-standardized mistletoe extract on breast cancer patients. A controlled epidemiological multicentric retrolective cohort study.

This epidemiological study was performed to evaluate the influence of postoperative complementary treatment with lectin-standardized mistletoe extract (sME) on breast cancer patients. The design (retrolective cohort analysis with parallel groups) and conduct of the study were in agreement with current standards for prospectively randomized clinical trials. A cohort of 1,248 breast cancer patients on postoperative chemo-, radio-, hormone-therapy were studied in 27 randomized centers. Patients with complementary medications other than sME were excluded from the evaluation and the final analysis was performed on data of 689 patients. From this cohort 219 patients received a complementary treatment exclusively with sME (therapy group), while 470 patients were without complementary treatment (control group). The median follow-up time was 284 days (therapy group) and 285 days (control group). The primary end-point of the study was to determine the impact of complementary sME treatment on disease- or therapy-induced adverse reactions in breast cancer patients. Imbalances for causal effects (covariates) were adjusted by propensity scores. Final evaluation was performed by estimating the linear regression between change in symptom score and propensity score with all data and using the regression line to calculate the change in symptom score expected for each patient. Tumor-associated events were evaluated by number and time until event. The safety of sME treatment was analysed in terms of number, severity, duration and outcome of adverse reactions. As compared to breast cancer patients without complementary treatment (control group), the administration of sME (therapy group) resulted in a significant reduction of adverse reactions induced by the tumor-destructive therapies (e.g. nausea, gastro-intestinal tract symptoms, depression, fatigue, mental symptoms) and prolonged relapse-free intervals, most pronounced for UICC stages IIa and IIb. The rate of sME-associated adverse reactions was 12.8%. All side-effects were mild to moderate, predominantly local skin reactions and self-limiting without therapeutic intervention. Complementary treatment of breast cancer patients with lectin-standardized mistletoe extract (sME) proved to be a well tolerated optimization of standard tumor-destructive therapies, mainly improving quality of life and relapse-free intervals in defined UICC stages.

Adult↗

PubMed2005

Does preoperative transbronchial biopsy worsen the postsurgical prognosis of lung cancer? A propensity score-adjusted analysis.

STUDY OBJECTIVES: Our aim was to clarify the hypothesis that the postsurgical prognosis of patients with non-small cell lung cancer (NSCLC) proven by preoperative diagnostic transbronchial biopsy (TBLB) was worse than that of the patients with NSCLC determined at the time of surgery. DESIGN: We entered the propensity score as a continuous variable in the Cox proportional hazards model, along with the success/failure of TBLB and other covariates that were adjusted for the bias inherent to the success/failure of the TBLB examination. PATIENTS: Five hundred ninety-nine consecutive patients with NSCLC undergoing complete resection were divided into two groups. Pathologic diagnosis by TBLB was preoperatively determined in patients belonging to group 1 (n = 367). TBLB was unsuccessful and exploratory thoracotomy or thoracoscopy was followed by surgical resection in patients belonging to group 2 (n = 232). The overall recurrence-free survival rate was examined as the surgical outcomes. RESULTS: The postsurgical recurrence-free rate was significantly higher in group 2 than in group 1. Group 2 patients showed better prognosis than group 1 patients, even when the data between the two groups were adjusted by propensity score. When the groups were subdivided by the pathologic stage of disease, the subgroup consisting of group 2 patients with stage IA and IB lung cancer still showed a higher recurrence-free rate than those in group 1 by propensity score analysis. CONCLUSIONS: The postsurgical prognosis of the patients with NSCLC was significantly better if the preoperative TBLB was unsuccessful. This result suggested that advanced NSCLC had a tendency to be diagnosed with TBLB and, possibly, that the TBLB procedure might worsen the prognosis of patients with resectable NSCLC. We suggest that intraoperative diagnosis followed by the consecutive resection of NSCLC may be beneficial for improving the surgical outcomes of NSCLC patients.

Adenocarcinoma↗

PubMed1988

Asymmetric stratification. An outline for an efficient method for controlling confounding in cohort studies.

Confounding is usually controlled by either cross-stratification or multivariate modeling. The first approach is simple and intuitive, but it is not practical for controlling many factors. The second approach, although less intuitive, may provide a more efficient means for controlling many confounders, but its ability to control confounding depends on the appropriateness of the chosen model. Hybrid methods based on a multivariate confounder score or a propensity score combine the favorable characteristics of both methods and may be better suited for controlling many confounders. However, the resulting strata are defined by subranges of a multivariate model, and, therefore, may possess little intrinsic meaning. The authors propose the principle of asymmetric stratification to control efficiently a number of confounders in cohort studies while retaining the intuitive appeal and general framework of cross-stratification. The proposed method resembles a propensity score analysis but does not use a multivariate model to define the strata. Instead, strata are defined by the categories of only a subset of the original potential confounders. The authors also demonstrate how our proposed method can be implemented by an application of classification and regression trees (CART) (recursive partitioning), as outlined by Breiman et al. (Classification and Regression Trees. Belmont, CA: Wadsworth, 1984). Computer simulations and an actual example suggest that the proposed method is a potentially simpler alternative to the standard propensity score analysis. Specific recommendations on how the proposed method can be improved are also presented.

Aged↗

PubMed2005

Neurological outcome of conservative versus endovascular treatment of patients with asymptomatic high-grade carotid artery stenosis: a propensity score-adjusted analysis.

PURPOSE: To report a propensity score-adjusted analysis of the long-term risks for stroke after carotid artery stenting (CAS) compared to medical therapy in patients with asymptomatic high-grade carotid artery stenosis. METHODS: A total of 946 consecutive patients (605 men; median age 73 years) with asymptomatic high-grade carotid artery stenoses (> or =70%) identified in a single center registry were treated either medically (n=525) or with CAS (n=421). A propensity score-adjusted analysis was performed to test the hypothesis that long-term neurological outcome might be better after CAS than after medical treatment, depending on the baseline degree of carotid stenosis and the patient's medical status. Baseline degree of stenosis was classified as 70% to 79% (n=307), 80% to 89% (n=366), and 90% to 99% (n=272) by duplex ultrasound. Surgical risk was estimated by the American Society of Anesthesiologists (ASA) score (I to IV). RESULTS: Stroke-free survival rates at 1, 3, and 5 years were 97%, 93%, and 89% after conservative treatment versus 94%, 93%, and 91% after CAS (p=0.56), respectively. Compared to conservatively treated patients with 70% to 79% stenoses, the adjusted hazard ratios for stroke were 2.36 (p=0.044) for conservatively treated patients with 80% to 89% and 3.17 (p=0.026) for those with 90% to 99% stenoses. For CAS patients with 70% to 79%, 80% to 89%, and 90% to 99% stenoses, the adjusted hazard ratios for stroke were 1.32 (p=0.63), 0.91 (p=0.84), and 0.98 (p=0.98) irrespective of the ASA score, the propensity to undergo CAS, and other potential confounders. Thus, the risk of stroke increased in parallel with the degree of stenosis in conservatively treated patients, but remained unchanged in patients undergoing CAS. CONCLUSIONS: Patients with asymptomatic severe carotid narrowing (> or =80%) might benefit from CAS with respect to stroke-free survival. Randomized controlled trials are needed to confirm these findings.

Aged↗

PubMed2026

Endovascular treatment after stroke beyond 24 h vs 6-24 h: a propensity score-matched cohort study.

BACKGROUND: Endovascular thrombectomy (EVT) is the standard treatment for acute ischemic stroke due to anterior circulation large vessel occlusion (LVO) within 6-24 h. However, the safety and feasibility of EVT for anterior circulation strokes beyond 24 h remain uncertain. METHODS: We conducted a retrospective cohort study of consecutive patients with anterior circulation LVO who underwent EVT at Changhai Hospital from 2018 to 2023. Patients were stratified into late (6-24 h) and very late (>24 h) windows. Propensity score matching (PSM) was performed to adjust for baseline imbalances, including age, sex, NIHSS, ASPECTS, occlusion location, perfusion parameters, and vascular risk factors. The primary outcome was functional independence (modified Rankin Scale [mRS] ≤ 2) at 3 months. Secondary outcomes included successful reperfusion (TICI 2b-3) and symptomatic intracranial hemorrhage (sICH). RESULTS: Among 1043 screened patients, 429 patients with anterior circulation LVO were included after exclusions, comprising 373 in the late window and 56 in the very late window. PSM yielded 42 matched pairs. Compared with the late window group, the very late window group showed no statistically significant differences in functional independence (54.8% vs. 57.1%; OR = 0.908, 95% CI 0.382-2.153, p = 0.830), successful reperfusion (88.1% vs. 92.9%; OR = 1.800, 95% CI 0.481-7.096, p = 0.460), sICH (2.4% vs. 9.5%; OR = 0.232, 95% CI 0.012-1.652, p = 0.200), intraprocedural complications (26.2% vs. 19.0%; OR = 1.508, 95% CI 0.540-4.362, p = 0.440), or postoperative complications (33.3% vs. 35.7%; OR = 0.900, 95% CI 0.363-2.219, p = 0.820). CONCLUSIONS: In this selected, single-center cohort of anterior circulation LVO patients undergoing EVT, treatment initiated beyond 24 h appeared to have comparable effectiveness and safety to treatment initiated within 6-24 h. Definitive evidence requires confirmation from adequately powered randomized controlled trials.

Humans↗

PubMed2026

Sex Differences in Postoperative Recovery and Mortality After High-Risk Cardiac Surgery: A Propensity Score-Matched Post Hoc Analysis of the SUSTAIN-CSX Trial.

BACKGROUND: Sex-related differences after cardiac surgery remain controversial because women often present with higher baseline risk and complexity than men. We performed a post hoc propensity score-matched analysis of the SUSTAIN-CSX (Sodium Selenite Administration in Cardiac Surgery) trial to evaluate sex differences in mortality, postoperative complications, and recovery after high-risk cardiac surgery. METHODS: Of 1394 trial participants, 1386 had complete data. Women were matched 1:1 to men using nearest-neighbor propensity score matching based on age and European System for Cardiac Operative Risk Evaluation II (EuroSCORE II), with exact matching on surgical category, yielding 327 female-male pairs. Prespecified sensitivity analyses adjusted for frailty, baseline hemoglobin, renal disease, left ventricular ejection fraction, previous myocardial infarction, preoperative medications, and baseline creatinine. RESULTS: In the primary matched analysis, 180-day survival did not differ between women and men (log-rank P=0.086; unadjusted hazard ratio, 1.80 [95% CI, 0.91-3.55]; P=0.091). In descriptive matched comparisons, women had numerically longer intensive care unit stay (median, 3 days [quartile 1, quartile 3 (Q1, Q3)=1, 6 days] versus 2 days [Q1, Q3=1, 5 days]) and hospital stay (median, 10 days [Q1, Q3=7, 18 days] versus 9 days [Q1, Q3=6, 16 days]; P=0.292), whereas major postoperative complications were similar. In adjusted sensitivity analyses accounting for the matched design and residual imbalance, female sex remained associated with longer intensive care unit stay (adjusted incidence rate ratio [IRR], 1.8 [95% CI, 1.2-2.9]; P=0.009) and hospital stay (adjusted IRR, 1.4 [95% CI, 1.0-1.9]; P=0.031). Mortality sensitivity analyses were model-dependent. CONCLUSIONS: In this propensity score-matched cohort of high-risk cardiac surgery patients, women showed a longer postoperative recovery trajectory in adjusted analyses, whereas mortality findings were sensitive to model specification and should be interpreted cautiously. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02002247.

Aged↗

PubMed2026

Oxymetazoline hydrochloride nasal spray for nasal function recovery after endoscopic transsphenoidal pituitary adenectomy: a propensity score-matched cohort study.

OBJECTIVE: To evaluate whether short-term adjunctive oxymetazoline hydrochloride nasal spray is associated with improved early nasal recovery after endoscopic transnasal transsphenoidal surgery for pituitary adenoma. METHODS: This single-center retrospective propensity score-matched cohort study included adults undergoing first-time endoscopic transnasal transsphenoidal surgery between January 2021 and December 2024. Patients receiving oxymetazoline hydrochloride 0.05% nasal spray plus routine saline irrigation were compared with those receiving saline irrigation alone. The primary outcome was longitudinal change in Nasal Obstruction Symptom Evaluation (NOSE) score from postoperative baseline to weeks 1, 2, and 4. Secondary outcomes included endoscopic nasal findings, nasal comfort, responder-defined NOSE improvement, and short-term safety outcomes. RESULTS: Among 860 eligible patients, 630 remained after 1:1 propensity score matching, with 315 patients in each group. Baseline covariates and postoperative pre-intervention nasal status were well balanced. Adjunctive oxymetazoline was associated with lower NOSE scores and modestly more favorable endoscopic findings and nasal comfort during early follow-up, although the absolute between-group differences were small and attenuated by week 4. Responder analyses based on ≥ 30% NOSE score reduction showed no statistically significant between-group differences. Major postoperative nasal complications were comparable between groups. Potentially drug-related adverse reactions occurred in 55 patients in the oxymetazoline group (17.5%), mainly mild local symptoms, and no serious drug-related adverse events or treatment discontinuations were documented. CONCLUSIONS: Short-term adjunctive oxymetazoline combined with routine saline irrigation was associated with modest early nasal recovery benefits after endoscopic transnasal transsphenoidal surgery. Its use should remain cautious, selective, and time-limited, pending prospective confirmation of clinical benefit and long-term safety.

Humans↗

PubMed2006

Body mass index: a risk factor for 30-day or six-month mortality in patients undergoing aortic valve replacement?

BACKGROUND AND AIM OF THE STUDY: In recent studies, the impact of a low or high body mass index (BMI) on outcome after cardiac surgery has been the subject of controversy. A retrospective study was conducted to determine the influence of BMI on 30-day and six-month mortality after aortic valve replacement (AVR). METHODS: A multivariable logistic regression was performed on data from 1,241 consecutive patients (mean age 69 +/- 11 years) who underwent AVR either with (n = 514; 41%) or without coronary artery bypass grafting CABG between 2000 and 2003. A wide spectrum of periprocedural variables was collected, including laboratory data as markers for nutritional status and comorbidity. Patients were followed up for six months after AVR (99% complete). RESULTS: Mortality rates after 30 days and after six months were 3.9% (n = 49) and 7.6% (n = 94), respectively. A low BMI was identified as an independent risk factor for 30-day (OR (odds ratio) 0.87; CI (confidence interval) 0.8-0.94) and six-month mortality (OR 0.91; CI 0.86-0.96). The relationship between the logit function and BMI was linear; however, a BMI value of 24 was considered an appropriate cut-off point. Both models containing the BMI linearly or dichotomic were equivalent. As patients with a lower BMI differ in their preoperative risk profile compared to those with a higher BMI, a saturated propensity score estimating the propensity towards having a BMI < 24 was calculated. The propensity score was not significant in the final models for 30-day and six-month mortality (0.24 and 0.73, respectively), and the OR for BMI remained largely unaltered (0.89 and 0.91, respectively). CONCLUSION: A BMI < 24 is predictive of an increased risk of mortality after AVR, independently of malnutrition, advanced heart disease, or valve size. Further studies are required to investigate the role of adipose tissue in extreme situations and chronic disease. It is mandatory to include BMI in outcome studies after AVR.

Aged↗

PubMed2026

Higher Rates of PASS and SCB After Arthroscopic Subspine Decompression Are Associated With a Positive Diagnostic AIIS Injection: A Propensity Score-Matched Cohort Study.

BACKGROUND: Hip arthroscopy effectively treats femoroacetabular impingement syndrome (FAIS), but persistent pain may be related to concomitant extra-articular pathology such as subspine impingement syndrome (SSI). Standard diagnosis of SSI often relies on 3-dimensional computed tomography (3D-CT) morphology (Hetsroni type II/III), although this morphology is common in individuals who are asymptomatic and correlates poorly with symptoms. PURPOSE: To compare minimum 2-year clinical outcomes after arthroscopic subspine decompression in patients with concurrent FAIS and type II/III anterior inferior iliac spine (AIIS) morphology, stratified by diagnostic method: 3D-CT morphology alone versus 3D-CT morphology plus a positive ultrasound-guided diagnostic injection. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This study included patients aged 18 to 55 years with type II/III AIIS morphology who underwent primary hip arthroscopy for FAIS and SSI between January 2021 and November 2023 and had minimum 2-year follow-up. Patients diagnosed by CT morphology alone (CT classification group) were propensity score matched 1:1 to patients with a positive ultrasound-guided AIIS injection (injection group), with 57 patients per group. Matching variables were age, sex, body mass index, lateral center-edge angle, alpha angle, Tönnis grade, and Beighton score. All patients underwent arthroscopic subspine decompression. Patient-reported outcomes and rates of achieving the minimal clinically important difference, Patient Acceptable Symptom State (PASS), and substantial clinical benefit (SCB) were compared. RESULTS: Preoperative patient-reported outcome scores were similar between groups (all P > .05). At minimum 2-year follow-up, the injection group had significantly better scores on the modified Harris Hip Score (90.8 vs 84.2), Hip Outcome Score-Activities of Daily Living (88.4 vs 82.4), Hip Outcome Score-Sports Subscale (71.9 vs 64.1), 12-item International Hip Outcome Tool (83.9 vs 76.1), and visual analog scale for pain (1.2 vs 2.0) (all P < .001). Minimal clinically important difference rates were high in both groups, with higher rates in the injection group for modified Harris Hip Score (93% vs 77%; P = .033) and Hip Outcome Score-Activities of Daily Living (91% vs 75%; P = .042). PASS and SCB rates were significantly higher in the injection group across all patient-reported outcome measures (all P < .05). Revision and complication rates were low and did not differ significantly between groups. CONCLUSION: Both groups improved significantly after arthroscopic subspine decompression. However, patients with a positive ultrasound-guided diagnostic AIIS injection achieved higher PASS and SCB rates than those selected by CT morphology alone, suggesting that injection-confirmed SSI may improve patient selection for subspine decompression.

Humans↗

PubMed1992

Estimating exposure effects by modelling the expectation of exposure conditional on confounders.

In order to estimate the causal effects of one or more exposures or treatments on an outcome of interest, one has to account for the effect of "confounding factors" which both covary with the exposures or treatments and are independent predictors of the outcome. In this paper we present regression methods which, in contrast to standard methods, adjust for the confounding effect of multiple continuous or discrete covariates by modelling the conditional expectation of the exposures or treatments given the confounders. In the special case of a univariate dichotomous exposure or treatment, this conditional expectation is identical to what Rosenbaum and Rubin have called the propensity score. They have also proposed methods to estimate causal effects by modelling the propensity score. Our methods generalize those of Rosenbaum and Rubin in several ways. First, our approach straightforwardly allows for multivariate exposures or treatments, each of which may be continuous, ordinal, or discrete. Second, even in the case of a single dichotomous exposure, our approach does not require subclassification or matching on the propensity score so that the potential for "residual confounding," i.e., bias, due to incomplete matching is avoided. Third, our approach allows a rather general formalization of the idea that it is better to use the "estimated propensity score" than the true propensity score even when the true score is known. The additional power of our approach derives from the fact that we assume the causal effects of the exposures or treatments can be described by the parametric component of a semiparametric regression model. To illustrate our methods, we reanalyze the effect of current cigarette smoking on the level of forced expiratory volume in one second in a cohort of 2,713 adult white males. We compare the results with those obtained using standard methods.

Analysis of Variance↗

PubMed2004

Primary patency of femoropopliteal arteries treated with nitinol versus stainless steel self-expanding stents: propensity score-adjusted analysis.

PURPOSE: To evaluate, in a propensity score-adjusted analysis, the intermediate-term primary patency rates associated with nitinol versus stainless steel self-expanding stent placement for treatment of atherosclerotic lesions in femoropopliteal arteries. MATERIALS AND METHODS: The authors analyzed the clinical and imaging data of 175 consecutive patients with peripheral artery disease and either intermittent claudication (n = 150) or critical limb ischemia (n = 25) who underwent femoropopliteal artery implantation of nitinol (n = 104) or stainless steel (n = 123) stents in a nonrandomized setting. The stents were placed owing to either significant residual stenosis (ie, >30% lumen diameter reduction) or flow-limiting dissection after initial balloon angioplasty of the femoropopliteal artery. Patients were followed up for a median period of 9 months (mean, 13 months; range, 6-66 months) for the detection of a first in-stent restenosis, defined as a greater than 50% lumen diameter reduction that was seen at color-coded duplex ultrasonography and confirmed at angiography. RESULTS: Cumulative patency rates at 6, 12, and 24 months were 85%, 75%, and 69%, respectively, after nitinol stent placement versus 78%, 54%, and 34%, respectively, after stainless steel stent placement (P =.008, log-rank test). There were no statistically significant differences in associated patency among the three different nitinol stents used (P =.72, log-rank test). Multivariate Cox proportional hazard analysis, in which the effect of propensity to receive a nitinol stent was considered, revealed a significantly reduced risk of restenosis with the nitinol stents compared with the risk of restenosis with the stainless steel stents (adjusted hazard ratio, 0.44; 95% confidence interval: 0.22, 0.85; P =.014). CONCLUSION: Nitinol stents are associated with significantly improved primary patency rates in femoropopliteal arteries compared with stainless steel stents. Randomized controlled trials are needed to confirm these results.

Aged↗

PubMed2005

Comparison of costs and utilization between users of insulin lispro versus users of regular insulin in a managed care setting.

OBJECTIVE: To compare medical and pharmacy costs and utilization between patients with diabetes who received insulin lispro versus regular human insulin. METHODS: A retrospective analysis of medical and pharmacy claims was conducted among continuously enrolled users of insulin lispro or regular insulin during the identification period, March 1, 2000, through February 28, 2001, within a large managed care organization. This study improved upon the methodology used in previous studies by (a) stratifying (rather than 1:1 matching) individuals by their likelihood to use insulin lispro using the propensity score binning technique, and (b) refining the study inclusion criteria to include only patients with 3 or more fills of the insulin under study (lispro or regular) to exclude individuals who may have been on either product for a short time. Because the propensity score binning technique groups patients with similar baseline characteristics within strata (bins) and not among individual patients, almost the entire available sample is retained in the analysis, unlike propensity score matching, where large numbers of patients can be excluded depending on the matching scheme. Therefore, the propensity score binning technique, because it uses more complete information, is less likely to produce biased results. Patients were grouped into 5 bins (quintiles) based on their estimated likelihood to receive insulin lispro rather than regular insulin. The propensity score model used baseline characteristics of age, gender, comorbidities, use of oral antidiabetic medications, prescription copayment, and diabetes-related costs and utilization. Overall cost and utilization differences (lispro minus regular insulin) during the 12-month follow-up period were calculated using weights inversely proportional to variances of within-bin differences. RESULTS: Of 6,436 patients, 1,972 (30.6%) received insulin lispro and 4,464 (69.4%) received regular insulin. The propensity score estimation produced 5 bins, each containing between 1,287 and 1,288 patients, utilizing all patients in the analysis. Patients in the lower-numbered propensity score quintiles were older, more likely to use oral antidiabetic medications, and had more comorbidities than those in the higher-numbered quintiles. As quintile number increased, the percentage of insulin lispro users also increased. The weighted mean annual cost difference (lispro minus regular insulin) per patient was + USD 79 (P < 0.001) for diabetes-related pharmacy cost, + USD 212 (P < 0.001) for total pharmacy cost, USD 75 (P < 0.857) for diabetes-related medical cost, USD 2,286 (P <0.011) for nondiabetes medical cost, and USD 2,327 (P = 0.072) for total medical cost. CONCLUSIONS: Compared with regular insulin users, insulin lispro users incurred higher diabetes-related and total pharmacy costs but lower nondiabetes medical costs and similar total medical costs. Fewer hospitalizations among insulin lispro as compared with regular insulin users contributed to lower nondiabetes medical costs and similar total medical costs.

Age Factors↗

PubMed2005

On-pump versus off-pump surgical revascularization for left main stem stenosis: risk adjusted outcomes.

BACKGROUND: Recent publications have shown coronary surgery is safe and effective in patients with critical left main stem stenosis when using off-pump coronary surgery techniques. However, these studies were small and did not adjust for differences in case mix. METHODS: Between April 1997 and March 2003, 1,197 consecutive patients with critical left main stem stenosis (> 50%) underwent coronary surgery. Two hundred and fifty-nine (21.6%) of these patients had off-pump coronary surgery, while 938 (78.4%) received on-pump coronary surgery. Multivariate logistic regression and Cox proportional hazards analysis were used to assess the effect of off-pump coronary surgery on outcomes, while adjusting for patient characteristics (treatment selection bias). Treatment selection bias was controlled by constructing a propensity score from core patient characteristics. The propensity score was the probability of receiving off-pump coronary surgery and was included along with the comparison variable in the multivariable analyses of outcome. RESULTS: After adjusting for the propensity score, the requirement for inotropic support (22.4% versus 35.3%; p < 0.001) or a prolonged length of stay (5.3% versus 9.3%; p = 0.034) were significantly reduced after receiving off-pump coronary surgery. There was a trend to suggest that off-pump patients had a lower incidence of stroke and chest infection. The adjusted freedom from death in off-pump patients at 2 years was 94.6% compared with 93.6% for on-pump patients (p = 0.54). CONCLUSIONS: After risk adjustment, patients with critical left main stem stenosis can undergo off-pump coronary surgery safely, with results comparable with on-pump coronary surgery.

Aged↗

PubMed2004

Effect of training on outcomes following coronary artery bypass graft surgery.

OBJECTIVE: We examined our coronary artery bypass surgery (CABG) experience to assess the effect of training on mortality and morbidity outcomes. METHODS: Between April 1997 and September 2002, 5678 consecutive patients underwent isolated CABG. Five hundred and fifty-five (9.9%) were performed by trainee surgeons. Multivariate logistic regression was used to assess the effect of training on adverse outcomes, while adjusting for patient and disease characteristics (treatment selection bias). Cox proportional hazards analysis was used to adjust Kaplan-Meier survival curves. Treatment selection bias was controlled for by constructing a propensity score from core patient characteristics including the additive EuroSCORE. The propensity score was the probability of CABG performed by trainee, with a C-statistic of 0.79, and was included along with the comparison variable (trainee vs Consultant) in a multivariable analysis of outcome. The propensity score is used as the sole variable for adjustment due to the low number of events, providing a more complete risk adjustment. RESULTS: CABG procedures performed by trainee surgeons were less likely to be female, hypertensive, obese, triple-vessel disease, redo and emergency cases. Also, trainee surgeons were less likely to operate on patients with cerebrovascular disease, renal dysfunction, and previous myocardial infarctions, prior gastrointestinal surgery, and poor left ventricular ejection fraction. The additive EuroSCORE was 2.9 in trainee cases compared to 3.5 in Consultant led cases (P<0.001) Crude outcomes were significantly better in trainee CABGs due to selection bias. In-hospital results were no longer significantly different between both groups after adjusting for the propensity score. The adjusted freedom from death in the trainee cases at 30 days, 1, 2, 3, and 4 years was 98.1, 96.2, 94.7, 93.2 and 91.8%, respectively, compared to 97.9, 95.7, 94.1, 92.3 and 90.8% for the Consultant led cases (P=0.53). CONCLUSIONS: After adjusting for case-mix, with careful case selection, training does not adversely affect the early and mid-term outcomes of CABG.

Aged↗

PubMed2003

A propensity score-matched cohort study of the effect of statins, mainly fluvastatin, on the occurrence of acute myocardial infarction.

This investigation quantified the effect of statins on acute myocardial infarction (AMI) in an observational setting where fluvastatin represented most of the statin use. The study applied propensity scores to match statin initiators to statin noninitiators and followed them for the occurrence of AMI. Serum low-density lipoprotein levels were reduced by statin therapy, and there were fewer incidents of AMI in statin initiators than in noninitiators.

Cholesterol, LDL↗

PubMed2002

Endovascular stent grafting versus open surgical operation in patients with infrarenal aortic aneurysms: a propensity score-adjusted analysis.

BACKGROUND: Although transfemoral endovascular aneurysm management (TEAM) of infrarenal abdominal aortic aneurysms (AAA) is widely performed, open graft replacement is still considered the standard of care. The aim of this study was to investigate whether clear indications for TEAM can be established in patients with significant comorbidities without investigating differences in relative procedure efficacy or durability. METHODS AND RESULTS: A propensity score-based analysis of 454 consecutive patients treated electively for AAA from January 1995 through December 2000 was performed. Of those 454 patients, 248 received open surgery and 206 received TEAM. In-hospital mortality rates (MRs) were compared. After adjusting for propensity scores, a Cox proportional hazard model (COX) was employed to test the influence of the respective treatment on postoperative 900-day survival estimates (SEs). Several potential preoperative risk factors were used as covariates. The MR of all patients was 3.7%. Explorative analysis demonstrated that patients treated by TEAM presented with significantly more risk factors. In American Society of Anesthesiologists class IV patients, a significant difference in MR was detected (4.7% for TEAM versus 19.2% for open surgery; P<0.02). After adjusting for the propensity to receive TEAM or open surgery, a regression analysis of survival based on COX revealed predictive influences of impaired kidney (P<0.047) or pulmonary function (P<0.001), increased age (P<0.05), and selection of treatment modality (P<0.002) on SE. CONCLUSIONS: TEAM represents a less invasive procedure for AAA therapy in patients with significant preoperative risk factors. Especially in geriatric patients with multiple morbidities, TEAM offers a method of therapy with acceptable MRs and SEs, making active treatment possible in otherwise incurable patients.

Adult↗

PubMed2004

Methods to assess intended effects of drug treatment in observational studies are reviewed.

BACKGROUND AND OBJECTIVE: To review methods that seek to adjust for confounding in observational studies when assessing intended drug effects. METHODS: We reviewed the statistical, economical and medical literature on the development, comparison and use of methods adjusting for confounding. RESULTS: In addition to standard statistical techniques of (logistic) regression and Cox proportional hazards regression, alternative methods have been proposed to adjust for confounding in observational studies. A first group of methods focus on the main problem of nonrandomization by balancing treatment groups on observed covariates: selection, matching, stratification, multivariate confounder score, and propensity score methods, of which the latter can be combined with stratification or various matching methods. Another group of methods look for variables to be used like randomization in order to adjust also for unobserved covariates: instrumental variable methods, two-stage least squares, and grouped-treatment approach. Identifying these variables is difficult, however, and assumptions are strong. Sensitivity analyses are useful tools in assessing the robustness and plausibility of the estimated treatment effects to variations in assumptions about unmeasured confounders. CONCLUSION: In most studies regression-like techniques are routinely used for adjustment for confounding, although alternative methods are available. More complete empirical evaluations comparing these methods in different situations are needed.

Confounding Factors, Epidemiologic↗