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PubMed2006

Assessing the effect of HAART on change in quality of life among HIV-infected women.

BACKGROUND: The impact of highly active antiretroviral therapy (HAART) on health-related quality of life (QOL) of HIV-1 infected individuals in large prospective cohorts has not been well studied. OBJECTIVE: To assess the effect of HAART on QOL by comparing HIV-infected women using HAART with HIV-infected women remaining HAART naïve in the Women's Interagency HIV Study (WIHS), a multicenter prospective cohort study begun in 1994 in the US. METHODS: A 1:1 matching with equivalent (<or= 0.1%) propensity scores for predicting HAART initiation was implemented and 458 pairs were obtained. HAART effects were assessed using pattern mixture models. The changes of nine QOL domain scores and one summary score derived from a shortened version of the MOS-HIV from initial values were used as study outcomes. RESULTS: The background covariates of the treatment groups were well-balanced after propensity score matching. The 916 matched subjects had a mean age of 38.5 years and 42% had a history of AIDS diagnosis. The participants contributed a total of 4,292 person visits with a median follow-up time of 4 years. In the bivariate analyses with only HAART use and time as covariates, HAART was associated with short-term improvements of 4 QOL domains: role functioning, social functioning, pain and perceived health index. After adjusting for demographic, socioeconomic, biological and clinical variables, HAART had small but significant short-term improvements on changes in summary QOL (mean change: 3.25; P = 0.02), role functioning (6.99; P < 0.01), social functioning (5.74; P < 0.01), cognitive functioning (3.59; P = 0.03), pain (6.73; P < 0.01), health perception (3.67; P = 0.03) and perceived health index (4.87; P < 0.01). These QOL scores typically remained stable or declined over additional follow-up and there was no indication that HAART modified these trends. CONCLUSION: Our study demonstrated significant short-term HAART effects on most QOL domains, but additional use of HAART did not modify long-term trends. These changes could be attributed to the direct effect of HAART and indirect HAART effect mediated through clinical changes.

Journal Article↗

PubMed2003

Early and midterm clinical outcome in patients with severe left ventricular dysfunction undergoing coronary artery surgery.

BACKGROUND: Patients presenting with severe left ventricular (LV) dysfunction undergoing coronary artery surgery are at increased risk of perioperative morbidity and mortality. The present study investigated early and midterm outcomes in a consecutive series of patients with severe LV dysfunction undergoing coronary surgery at our institution. METHODS: Data on 5,195 consecutive patients undergoing coronary artery bypass grafting (CABG) alone (in-hospital mortality 1.35%) from April 1996 to August 2002 were prospectively recorded in the Patient Analysis and Tracking System. Two hundred and fifty patients (median age 65 years [interquartile range, 57 to 70]) with preoperative left ventricular ejection fraction less than 30% (74 off pump; 29.6%) were identified and early and midterm clinical outcomes analyzed. Propensity scores were used to take account of the imbalance in the distribution of prognostic factors between the on-pump and off-pump groups. RESULTS: Patients undergoing on-pump surgery were less likely to have current congestive heart failure, insulin-dependent diabetes, a history of hypertension, have had gastrointestinal tract surgery or an ulcer, or unstable angina. They had on average lower Parsonnet scores and New York Heart Association and Canadian Cardiovascular Score ratings. However they were more likely to have more extensive coronary artery heart disease and to require more grafts than those undergoing off-pump surgery. After adjustment for consultant team and propensity scores no differences between groups with regard to in-hospital mortality and morbidity were found. The only in-hospital outcome to show a significant difference after adjustment was the need for intraoperative inotropic support, which was higher in the on-pump group (odds ratio 5.1; 95% confidence interval 2.55 to 10.2; p < 0.001)). The median follow-up times for the on- and off-pump groups were 3.4 years and 1.4 years respectively. Three-year survival was higher with on-pump surgery (87% on-pump versus 73% off-pump) but this difference did not reach statistical significance after adjustment for prognostic variables (hazard ratio 0.54, 95% confidence interval 0.22 to 1.26, p = 0.16). CONCLUSIONS: In-hospital mortality and morbidity in patients presenting with severe LV dysfunction is low with comparable results with both on- and off-pump coronary artery surgery. Midterm clinical outcome is encouraging and seems to justify surgical revascularization for this high-risk group of patients.

Aged↗

PubMed2007

A note on sample size calculation based on propensity analysis in nonrandomized trials.

In nonrandomized trials, patients are not randomly assigned to treatment groups with equal probability. Instead, the probability of assignment varies from patient to patient depending on patients baseline covariates. This often results in a non-comparable treatment groups due to treatment imbalance. As a result, the United States Food and Drug Administration (FDA) recommended that the method of propensity score analysis be employed to overcome this problem. In this note, a formula for sample size calculation is developed based on a proposed weighted Mantel-Haenszel test on the strata defined by the propensity score analysis. It was shown that the sample size formula derived by Nam (1998) based on the test statistic proposed by Gart (1985) is a special case of the sample size formula derived in this note.

Algorithms↗

PubMed1996

The effectiveness of right heart catheterization in the initial care of critically ill patients. SUPPORT Investigators.

OBJECTIVE: To examine the association between the use of right heart catheterization (RHC) during the first 24 hours of care in the intensive care unit (ICU) and subsequent survival, length of stay, intensity of care, and cost of care. DESIGN: Prospective cohort study. SETTING: Five US teaching hospitals between 1989 and 1994. SUBJECTS: A total of 5735 critically ill adult patients receiving care in an ICU for 1 of 9 prespecified disease categories. MAIN OUTCOME MEASURES: Survival time, cost of care, intensity of care, and length of stay in the ICU and hospital, determined from the clinical record and from the National Death Index. A propensity score for RHC was constructed using multivariable logistic regression. Case-matching and multivariable regression modeling techniques were used to estimate the association of RHC with specific outcomes after adjusting for treatment selection using the propensity score. Sensitivity analysis was used to estimate the potential effect of an unidentified or missing covariate on the results. RESULTS: By case-matching analysis, patients with RHC had an increased 30-day mortality (odds ratio, 1.24; 95% confidence interval, 1.03-1.49). The mean cost (25th, 50th, 75th percentiles) per hospital stay was $49 300 ($17 000, $30 500, $56 600) with RHC and $35 700 ($11 300, $20 600, $39 200) without RHC. Mean length of stay in the ICU was 14.8 (5, 9, 17) days with RHC and 13.0 (4, 7, 14) days without RHC. These findings were all confirmed by multivariable modeling techniques. Subgroup analysis did not reveal any patient group or site for which RHC was associated with improved outcomes. Patients with higher baseline probability of surviving 2 months had the highest relative risk of death following RHC. Sensitivity analysis suggested that a missing covariate would have to increase the risk of death 6-fold and the risk of RHC 6-fold for a true beneficial effect of RHC to be misrepresented as harmful. CONCLUSION: In this observational study of critically ill patients, after adjustment for treatment selection bias, RHC was associated with increased mortality and increased utilization of resources. The cause of this apparent lack of benefit is unclear. The results of this analysis should be confirmed in other observational studies. These findings justify reconsideration of a randomized controlled trial of RHC and may guide patient selection for such a study.

APACHE↗

PubMed1998

Health outcomes associated with beta-blocker and diltiazem treatment of unstable angina.

OBJECTIVE: We compared long-term health outcomes associated with beta-adrenergic blocking agents and diltiazem treatment for unstable angina. BACKGROUND: No long-term data have been published comparing these two antianginal treatments in this setting. METHODS: Eligible veterans were discharged from the Veterans Affairs Puget Sound Health Care System (VAPSHCS), Seattle Division, between October 1989 and September 1995 with an unstable angina diagnosis and were prescribed monotherapy beta-blocker or diltiazem treatment at discharge. Medication data were collected from medical records and computerized VAPSHCS outpatient pharmacy files. Follow-up death and coronary artery disease rehospitalization data were collected through 1996. Proportional hazards regression compared survival among diltiazem and beta-blocker users, controlling for patient characteristics with propensity scores. RESULTS: Two hundred forty-seven veterans (24% on beta-blockers, 76% on diltiazem) were included in this study. There were 54 (22%) deaths during an average follow-up of 51 months. After propensity score adjustment, there was no difference in risk of death comparing diltiazem to beta-blocker treatment (hazards ratios [HR] 1.1; 95% confidence interval [CI] 0.49 to 2.4). Among Washington residents (n=207), there were 146 (71%) coronary artery disease rehospitalizations or deaths during follow-up. After adjustment, there was a nonsignificant increase in risk of rehospitalization or death associated with diltiazem use (HR 1.4; 95% CI 0.80 to 2.4). For both analyses, similar risks were found among veterans without relative contraindications to beta-blockers. CONCLUSIONS: We found no survival benefit of diltiazem over beta-blocker treatment for unstable angina in this cohort of veterans.

Adrenergic beta-Antagonists↗

PubMed2003

Impact of timing of initiation of dialysis on mortality.

Previous studies showed that sicker patients were initiated on dialysis at higher GFR as estimated by the Modification of Diet in Renal Disease (MDRD) formula. It was previously shown that patients with low creatinine production were malnourished and had low serum creatinine levels and creatinine clearances (CrCl) but high MDRD GFR at initiation of dialysis. Therefore, a propensity score approach was used to examine the associations of MDRD GFR and measured CrCl at the initiation of dialysis with subsequent mortality. Baseline data and outcomes were obtained from the Dialysis Morbidity Mortality Study Wave II. Propensity scores for early initiation derived by logistic regression were used in Cox models to examine mortality. Each 5-ml/min increase in MDRD GFR at initiation of dialysis in the entire cohort was associated with increased hazard of death in multivariable Cox model (hazard ratio [HR] 1.14; P = 0.002). In the subgroup of patients with reported CrCl, higher MDRD GFR was associated with increased risk of death (for each 5-ml/min increase, HR 1.27; P < 0.001) but not CrCl (for each 5-ml/min increase, HR 0.98; P = 0.81). These divergent results might reflect erroneous GFR estimation by the MDRD formula. Furthermore, these data do not support earlier initiation of dialysis. Therefore, for patients without clinical indications for initiation of dialysis, the appropriate GFR level for initiation of dialysis is unknown.

Adult↗

PubMedDate not supplied

Estimating the cost-effectiveness of fluticasone propionate for treating chronic obstructive pulmonary disease in the presence of missing data.

OBJECTIVES: To explore the cost-effectiveness of fluticasone propionate (FP) for the treatment of chronic obstructive pulmonary disease (COPD), we estimated costs and quality-adjusted life-years (QALYs) over 3 years, based on an economic appraisal of a previously reported clinical trial (Inhaled Steroids in Obstructive Lung Disease in Europe [ISOLDE]). METHODS: Seven hundred forty-two patients enrolled in the ISOLDE trial who received either FP or placebo had data available on health-care costs and quality of life over the period of the study. The SF-36-based utility scores for quality of life were used to calculate QALYs. A combined imputation and bootstrapping procedure was employed to handle missing data and to estimate statistical uncertainty in the estimated cumulative costs and QALYs over the study period. The imputation approach was based on propensity scoring and nesting this approach within the bootstrap ensured that multiple imputations were performed such that statistical estimates included imputation uncertainty. RESULTS: Complete data were available on mortality within the follow-up period of the study and a nonsignificant trend toward improved survival of 0.06 (95% confidence interval [CI]-0.01 to 0.15) life-years was observed. In an analysis based on a propensity scoring approach to missing data we estimated the incremental costs of FP versus placebo to be 1021 sterling pound(95% CI 619-1338 sterling pound) with an additional effect of 0.11 QALYs (CI 0.04-0.20). Cost-effectiveness estimates for the within-trial period of 17,700 sterling pound per life-year gained (6900 sterling pound to infinity) and 9500 sterling pound per QALY gained (CI 4300-26,500 sterling pound) were generated that include uncertainty due to the imputation process. An alternative imputation approach did not materially affect these estimates. CONCLUSIONS: Previous analyses of the ISOLDE study showed significant improvement on disease-specific health status measures and a trend toward a survival advantage for treatment with FP. This analysis shows that joint considerations of quality of life and survival result in a substantial increase in QALYs favoring treatment with FP. Based on these data, the inhaled corticosteroid FP appears cost-effective for the treatment of COPD. Confirmation or refutation of this result may be achieved once the Towards a Revolution in COPD Health (TORCH) study reports, a large randomized controlled trial powered to detect mortality changes associated with the use of FP alone, or in combination with salmeterol, which is also collecting resource use and utility data suitable for estimating cost-effectiveness.

Administration, Inhalation↗

PubMed2006

The effects of radiotherapy for the treatment of contralateral breast cancer.

Radiotherapy following breast-conserving surgery for the treatment of first primary breast cancer is the standard of care and is widely used despite its small survival benefit. The effects of radiotherapy in metachronous contralateral breast cancer are unknown. We examined the use of radiotherapy and its effect on cause-specific and all-cause mortality among women with metachronous contralateral breast cancer treated with breast-conserving surgery in community settings. Using data from the 1985-2000 Surveillance, Epidemiology, and End Results program, we identified women with stage 0-III metachronous contralateral breast cancer that occurred at least six months after stage 0-III first primary breast cancer. Cause-specific and all-cause mortality of women age 40-69 who did and who did not receive radiotherapy following breast-conserving surgery for metachronous contralateral breast cancer were compared in proportional hazard models using propensity scores to balance covariates by radiotherapy use. We adjusted for misclassification of radiotherapy use. Based on misclassification-corrected analyses, 43.2 percent of 1,083 women with metachronous contralateral breast cancer did not receive radiotherapy after BCS. After adjustment for propensity scores and radiotherapy misclassification, women who did not receive radiotherapy had 2.2 times greater risk of cause-specific and 1.7 times greater risk of all-cause mortality. In community settings, a high percentage of women with stage 0-III metachronous contralateral breast cancer did not receive radiotherapy following breast-conserving surgery. Unlike the small survival benefit of radiotherapy after first primary breast cancer, omission of radiotherapy after metachronous contralateral breast cancer significantly increased the risk of cause-specific and all-cause mortality.

Adult↗

PubMed2006

Does prophylactic sotalol and magnesium decrease the incidence of atrial fibrillation following coronary artery bypass surgery: a propensity-matched analysis.

BACKGROUND: Atrial fibrillation can occur in up to 40% of patients undergoing coronary surgery. METHODS: We retrospectively analysed 103 consecutive coronary surgery patients under the care of one surgeon between April 2003 and September 2003. These patients received 40 mg of sotalol orally twice daily from the first post-operative day for 6 weeks and 2 g of magnesium intravenously immediately post surgery and on the first post-operative day. We developed a propensity score for the probability of receiving sotalol and magnesium after coronary surgery. 89 patients from the sotalol and magnesium group were successfully matched with 89 unique coronary surgery patients who did not receive either sotalol or magnesium with an identical propensity score. RESULTS: Preoperative characteristics were well matched between groups. There was no significant difference with respect to in-hospital mortality between groups (sotalol and magnesium 1.1% versus control 4.5%; p = 0.17). The incidence of atrial fibrillation in the sotalol and magnesium group was 13.5% compared to 27.0% in the controls (p = 0.025). CONCLUSION: The combination of sotalol and magnesium can significantly reduce the incidence of post-operative atrial fibrillation following coronary surgery.

Administration, Oral↗

PubMed2004

Association between congestive heart failure and hospitalization in patients with type 2 diabetes mellitus receiving treatment with insulin or pioglitazone: a retrospective data analysis.

BACKGROUND: Thiazolidinediones (TZDs) are widely used oral antihyperglycemic drugs that facilitate insulin action and increase insulin-stimulated glucose metabolism, thereby decreasing insulin resistance. However, concerns have been raised regarding the association between TZD use and a heightened risk for congestive heart failure (CHF). OBJECTIVE: This study used claims data to conduct a retrospective examination of the CHF risk in patients with type 2 diabetes mellitus and to compare the association with CHF in those receiving the TZD pioglitazone and those receiving insulin. METHODS: Patients with type 2 diabetes aged > or =18 years who had begun treatment with pioglitazone or insulin between January 1999 and December 2001 were identified using the PharMetrics Patient-Centric database. The sample was restricted to patients for whom there were > or =12 months of data before the index date (date of the first prescription for pioglitazone or insulin) and > or =3 months of follow-up data. Patients receiving a diagnosis of CHF before the index date were excluded. The propensity score for receiving pioglitazone was estimated using logistic regression based on available observed patient characteristics. Patients receiving insulin were matched in a 1:1 ratio with patients receiving pioglitazone based on a difference of no more than +/-0.01 in the estimated propensity score for receiving pioglitazone therapy. CHF risk was examined using the Cox proportional-hazards model. RESULTS: After exclusion of ineligible patients, 1668 matched pairs of patients receiving pioglitazone or insulin were identified (50.9% men, 49.1% women; mean [SE] age, 51.2 [0.2] years). The 2-year crude incidence rate of CHF was significantly lower in the pioglitazone group compared with the insulin group (primary/secondary diagnosis of CHF, 2.0% vs 4.0%, respectively; P < 0.001; inpatient hospitalization for CHF, 0.7% vs 2.5%; P < 0.001). The hazard ratio for pioglitazone versus insulin was 0.501 (95% CI, 0.331-0.758; P = 0.001) for a primary or secondary diagnosis of CHF in any setting and 0.263 (95% CI, 0.135-0.511; P < 0.001) for any occurrence of an inpatient hospitalization for CHF. CONCLUSIONS: In this retrospective analysis of data from patients with type 2 diabetes, pioglitazone therapy was associated with significantly lower incidence rates of CHF and inpatient hospitalization compared with insulin therapy.

Cohort Studies↗

PubMed2004

On-pump versus off-pump coronary artery bypass surgery in a matched sample of women: a comparison of outcomes.

BACKGROUND: Women have consistently higher mortality and morbidity than men after coronary artery bypass grafting (CABG). Whether elimination of cardiopulmonary bypass and performance of coronary artery bypass grafting off-pump (OPCAB) have a beneficial effect specifically in women has not been defined. METHODS AND RESULTS: From January 1998 through March 2002, 21 902 consecutive female patients at 82 hospitals underwent isolated CABG, as reported in an administrative database. Propensity score computer matching was performed based on 13 variables representing patient characteristics and preoperative risk factors to correct for and minimize selection bias. A total of 7376 (3688 pairs) women undergoing CABG surgery were able to be successfully matched. In a propensity score computer-matched cohort, multivariate logistic regression (odds ratio) revealed that women undergoing on-pump surgery had a 73.3% higher mortality (P=0.002) and a 47.2% higher risk of bleeding complications (P=0.019). CONCLUSIONS: In a retrospective analysis of women undergoing CABG, computer-matched to minimize selection bias, off-pump surgery led to decreased mortality and morbidity including bleeding complications.

Aged↗

PubMed2005

Impact of mitral valve annuloplasty on mortality risk in patients with mitral regurgitation and left ventricular systolic dysfunction.

OBJECTIVES: This study was designed to assess effects of mitral valve annuloplasty (MVA) on mortality in patients with mitral regurgitation (MR) and left ventricular (LV) systolic dysfunction. BACKGROUND: Mitral valve annuloplasty improves hemodynamics and symptoms in these patients, but effects on long-term mortality are not well established. METHODS: We retrospectively analyzed consecutive patients with significant MR and LV systolic dysfunction on echocardiography between 1995 and 2002. Cox regression analysis, including MVA as a time-dependent covariate and propensity scoring to adjust for differing probabilities of undergoing MVA, was used to identify predictors of death, LV assist device implantation, or United Network for Organ Sharing-1 heart transplantation. RESULTS: Of 682 patients identified, 419 were deemed surgical candidates; 126 underwent MVA. Propensity score derivation identified age, ejection fraction, and LV dimension to be associated with undergoing MVA. End points were reached in 120 (41%) non-MVA and 62 (49%) MVA patients. Increased risk of end point was associated with coronary artery disease (hazard ratio [HR] 1.80, 95% confidence interval [CI] 1.30 to 2.49), blood urea nitrogen (HR 1.01, 95% CI 1.005 to 1.02), cancer (HR 2.77, 95% CI 1.45 to 5.30), and digoxin (HR 1.66, 95% CI 1.15 to 2.39). Reduced risk was associated with angiotensin-converting enzyme inhibitors (HR 0.65, 95% CI 0.44 to 0.95), beta-blockers (HR 0.59, 95% CI 0.42 to 0.83), mean arterial pressure (HR 0.98, 95% CI 0.97 to 0.99), and serum sodium (HR 0.93, 95% CI 0.90 to 0.96). Mitral valve annuloplasty did not predict clinical outcome. CONCLUSIONS: In this analysis, there is no clearly demonstrable mortality benefit conferred by MVA for significant MR with severe LV dysfunction. A prospective randomized control trial is warranted for further study of mortality with MVA in this population.

Aged↗

PubMed2006

Brief report: graduated compression stocking thromboprophylaxis for elderly inpatients: a propensity analysis.

BACKGROUND: Graduated compression stockings (GCS) are often used for deep vein thrombosis prophylaxis in nonsurgical patients, although evidence on their effectiveness is lacking in this setting. OBJECTIVE: To determine whether prophylaxis with GCS is associated with a decrease in the rate of deep vein thrombosis in nonsurgical elderly patients. METHODS: Using original data from 2 multicenter nonrandomized studies, we performed multivariable and propensity score analyses to determine whether prophylaxis with GCS reduced the rate of deep vein thrombosis among 1,310 postacute care patients 65 years or older. The primary outcome was proximal deep vein thrombosis detected by routine compression ultrasonography performed by registered vascular physicians. RESULTS: Proximal deep vein thrombosis was found in 5.7% (21/371) of the GCS users and in 5.2% (49/939) of the GCS nonusers (odds ratio [OR], 1.09; 95% confidence interval [CI], 0.64-1.84). Although adjusting for propensity score eliminated all differences in baseline characteristics between users and nonusers, the OR for proximal deep vein thrombosis associated with GCS remained nonsignificant in propensity-stratified (adjusted OR, 1.11; 95% CI, 0.59-2.10) and propensity-matched (conditional OR, 0.92; 95% CI, 0.42-2.02) analysis. Similar figures were observed for distal and any deep vein thrombosis. The rates of deep vein thrombosis did not differ according to the length of stockings. CONCLUSIONS: Prophylaxis with GCS is not associated with a lower rate of deep vein thrombosis in nonsurgical elderly patients in routine practice. Randomized studies are needed to assess the efficacy of GCS when properly used in this setting.

Aged↗

PubMed2005

Effect of risk-adjusted diabetes on mortality and morbidity after coronary artery bypass surgery.

BACKGROUND: Diabetes is commonly regarded as a risk factor for mortality and morbidity after coronary artery bypass surgery. METHODS: Between April 1997 and December 2002, 6,033 consecutive patients underwent isolated coronary artery bypass surgery. Eight hundred and fourteen (13.5%) patients had diabetes (530 oral-dependent, 284 insulin-dependent). Patients with diet-controlled diabetes were classified as nondiabetics. Deaths occurring over time were described using Kaplan-Meier techniques. To control for differences in patient characteristics, we constructed a propensity score (for diabetes) and this was included along with the comparison variable in multivariate logistic regression and Cox proportional hazards analyses. RESULTS: In-hospital mortality was significantly higher for diabetic patients in the univariate analyses; however, this association disappeared after adjusting for the propensity score. Further analyses found that insulin-dependent diabetes was associated with an increased incidence of acute renal failure (adjusted odds ratio 4.15; p = 0.002), deep sternal wound infection (adjusted odds ratio 2.96; p = 0.039), and prolonged postoperative stay (adjusted odds ratio 1.60; p = 0.017). Oral-controlled diabetes was not associated with any of these outcomes. Four hundred and ninety-eight (8.3%) deaths occurred during the study follow-up. After adjusting for patient characteristics, the adjusted hazard ratio of midterm mortality for diabetes was 1.35; p = 0.013. CONCLUSIONS: Insulin-dependent diabetes has a significant impact on in-hospital morbidity. Although diabetic patients are not at increased risk of in-hospital mortality, longevity is significantly decreased during a five-year follow-up period.

Acute Kidney Injury↗

PubMed2002

Primary angioplasty and selection bias inpatients presenting late (>12 h) after onset of chest pain and ST elevation myocardial infarction.

OBJECTIVES: This study was designed to compare the in-hospital outcome of patients presenting with >12 h from onset of chest pain and acute ST elevation myocardial infarction (AMI) who received either immediate invasive or conservative therapy. BACKGROUND: The benefits of fibrinolytic therapy diminish in patients presenting with AMI and onset of chest pain >12 h. Primary angioplasty has been suggested as a possible treatment for such patients, but they have been excluded from most trials of primary angioplasty. It remains unclear if an invasive treatment strategy is beneficial to these patients. METHODS: Patients presenting with >12 h of chest pain and AMI were identified from the National Registry of Myocardial Infarction 2 database. Patients receiving invasive therapy <6 h after hospital admission were compared with those receiving conservative therapy. Short-term outcomes were compared on the basis of the initial therapy received. To help control for baseline differences in the groups, patients were matched with controls by propensity score methodology. RESULTS: On preliminary analysis, in-hospital outcome was improved in terms of recurrent ischemia, angina, myocardial infarction and mortality in patients receiving initial invasive therapy (odds ratio [OR] = 0.67; 95% confidence interval [CI] 0.49 to 0.92 for mortality). After matching by propensity score, the mortality benefit persisted on bivariate analysis (3.5% vs. 5.0%, p = 0.036), though on multivariate analysis, only a non-significant but strong trend toward decreased mortality remained (OR = 0.73; 95% CI 0.53 to 1.01). CONCLUSIONS: Patients receiving early invasive therapy had lower risk features on presentation. Selection bias may play an important role in choosing these patients' course of treatment and their subsequent outcomes. Certain patients presenting with AMI and duration of chest pain >12 h may benefit from early invasive therapy. These patients could be characterized in a randomized trial.

Aged↗

PubMed2003

The impact of residual renal function on graft and patient survival rates in recipients of preemptive renal transplants.

BACKGROUND: Transplantation before the initiation of dialysis is associated with prolonged allograft survival. It is unclear if this benefit is attributable to greater residual renal function or to avoidance of dialysis exposure. The authors performed an analysis to determine whether higher renal function at transplant was associated with increased patient and graft survival rates. METHODS: The authors identified individuals who between 1994 and June 2000 were >or= 18 years and had undergone a living donor renal transplant (Tx) as initial form of renal replacement therapy. Pre-Tx and 6-month estimated glomerular filtration rates (eGFR) were calculated using the 4-variable Modification of Diet in Renal Disease formula. Survival was compared in those with a pre-Tx eGFR >or=15mL/min to those with an eGFR less than 15 mL/min, after adjusting for demographic variables, co-morbidities, and transplant characteristics. Survival rate then was adjusted for calculated propensity scores. RESULTS: A total of 4,046 patients were included. Mean pre-Tx eGFR was 9.9 mL/min (0.9 to 57.1 mL/min). There was no difference in graft survival rates by strata of eGFR in any of the tested models, even after correcting for propensity score (hazard ratio, 0.95; 95% confidence interval, 0.69 to 1.30). There was no correlation between pre-Tx eGFR and 6-month post-Tx eGFR (r(2) =-0.005). CONCLUSION: Recipients of preemptive transplants fare equally, regardless of the eGFR at which they receive their transplant. There was no relationship between pre-Tx eGFR and 6-month eGFR, suggesting that post-Tx renal function is independent of the level of pre-Tx renal function. These data suggest that preemptive kidney transplantation should be delayed as long as possible, provided the patient does not have uremic symptoms, and dialysis can be safely avoided.

Adult↗

PubMed2006

The risk of suicide with selective serotonin reuptake inhibitors in the elderly.

OBJECTIVE: The authors explored the relationship between the initiation of therapy with selective serotonin reuptake inhibitor (SSRI) antidepressants and completed suicide in older patients. METHOD: The authors linked population-based coroner's records with patient-level prescription data, physician billing claims, and hospitalization data for more than 1.2 million Ontario residents 66 years of age and older from 1992 to 2000. For each suicide case, four closely matched comparison subjects were selected using propensity score methods. The authors determined the odds ratio for suicide with SSRIs versus other antidepressant treatment, calculated at discrete monthly intervals from the start of treatment. RESULTS: Of 1,329 suicide cases, 1,138 (86%) were each fully matched to four comparison subjects using propensity scores. During the first month of therapy, SSRI antidepressants were associated with a nearly fivefold higher risk of completed suicide than other antidepressants (adjusted odds ratio: 4.8, 95% confidence interval=1.9-12.2). The risk was independent of a recent diagnosis of depression or the receipt of psychiatric care, and suicides of a violent nature were distinctly more common during SSRI therapy. Numerous sensitivity analyses revealed consistent results. No disproportionate suicide risk was seen during the second and subsequent months of treatment with SSRI antidepressants, and the absolute risk of suicide with all antidepressants was low. CONCLUSIONS: Initiation of SSRI therapy is associated with an increased risk of suicide during the first month of therapy compared with other antidepressants. The absolute risk is low, suggesting that an idiosyncratic response to these agents may provoke suicide in a vulnerable subgroup of patients.

Age Factors↗

PubMed2001

Methods for testing equality of means of health care costs in a paired design study.

In this paper we propose five new tests for the equality of paired means of health care costs. The first two tests are the parametric tests, a Z-score test and a likelihood ratio test, both derived under the bivariate normality assumption for the log-transformed costs. The third test (Z-score with jack-knife) is a semi-parametric Z-score method, which only requires marginal log-normal assumptions. The last two tests are the non-parametric bootstrap tests: one is based on a t-test statistic, and the other is based on Johnson's modified t-test statistic. We conduct a simulation study to compare the performance of these tests, along with some commonly used tests when the sample size is small to moderate. The simulation results demonstrate that the commonly used paired t-test on the log-scale and the Wilcoxon signed rank for differences of the two original scales can yield type I error rates larger than the preset nominal levels. The commonly used paired t-test on the original data performs well with slightly skewed data, but can yield inaccurate results when two populations have different skewness. The likelihood ratio test, the parametric and semi-parametric Z-score tests all have very good type I error control with the likelihood ratio test being the best. However, the semi-parametric Z-score test requires less distributional assumptions than the two parametric tests. The percentile-t bootstrap test and bootstrapped Johnson's modified t-test have better type I error control than the paired t-test on the original-scale and Johnson's modified t-test, respectively. Combining with the propensity-score method, we can also apply the proposed methods to test the mean equality of two cost outcomes in the presence of confounders. Our two applications are from health services research. In the first one, we want to know the effect of Medicaid reimbursement policy change on outpatient health care costs. The second one is to evaluate the effect of a hospitalist programme on health care costs in an observational study, and the imbalanced covariates between intervention and control patients are taken into account using a propensity score approach.

Computer Simulation↗