Biomedical subjects

Marshall Joffe

Publications and source records attributed to Marshall Joffe.

10 recordsLinked to original sources

PubMed2005

Impact of pediatric vaccination with pneumococcal conjugate vaccine on the risk of bacteremic pneumococcal pneumonia in adults.

Invasive pneumococcal disease in adults may be declining, reflecting a form of herd protection from a new pediatric pneumococcal conjugate vaccine. Our aim was to determine whether vaccination of children protects adults in the same home from bacteremic pneumococcal pneumonia. We conducted a case-control study with 43 participating hospitals across a five-county region in Pennsylvania. Eligible cases were adults with bacteremic pneumococcal pneumonia identified by the microbiology laboratories at participating hospitals. Controls were healthy adults from the region identified through random digit dialing. Cases and controls were interviewed by telephone. We analyzed vaccine protection in those adults who reported living in homes with at least one child < or =6 years of age. From April 2002 through June 2004, there was a significant decline in the proportion of adult pneumococcal bacteremia due to any of the seven serotypes in the conjugate vaccine (p=0.006). Within this time period, 17% of cases and controls reported living in homes with at least one child < or =6 years of age. In adjusted analysis, vaccination of the youngest child in the home was associated with an 80% reduction in the odds of bacteremic pneumococcal pneumonia among adults with children in the home (OR=0.2, 95% CI 0.1-0.8). We conclude that introduction of a pneumococcal conjugate vaccine for children has reduced the population rate of adult pneumococcal bacteremia due to vaccine serotypes and is associated with a reduced risk of bacteremic pneumococcal pneumonia for adults with children in the home.

Adult↗

PubMed2005

Influences of earlier adherence and symptoms on current symptoms: a marginal structural models analysis.

BACKGROUND: The morbidity and mortality associated with asthma are suspected to be a result, in part, of poor adherence to inhaled corticosteroid regimens. One influence on adherence may be the perception of symptoms. Because symptoms and adherence affect each other over time, a conventional statistical approach for studying these relationships may provide biased results. OBJECTIVE: To understand the influence of previous asthma symptoms and previous adherence on current symptoms. METHODS: A total of 76 adults, mean age 48 years +/- 15 years, with moderate or severe persistent asthma underwent 6 weeks of electronic monitoring of their use of inhaled corticosteroids and completed a daily symptom diary. We estimated the effect of earlier adherence on final symptoms by using marginal structural models, estimated by using a weighted estimation technique. RESULTS: Morning was better than evening adherence, which declined over the observation period. The variability of adherence appeared to increase over the observation period. In addition, earlier adherence predicted current adherence more strongly than earlier symptoms predicted current adherence. There was no overall significant relationship between cumulative adherence and final symptoms. CONCLUSION: These data indicate that accurately determining past adherence will help identify patients to target to improve their future adherence. These analyses are important for understanding time-varying measures in the clinical setting.

Administration, Inhalation↗

PubMed2004

Administration of parenteral iron and mortality among hemodialysis patients.

The objective of this study was to evaluate whether the apparent relationship demonstrated in prior studies between iron dosing and mortality in hemodialysis (HD) patients was confounded by incomplete representation of iron dosing and morbidity over time. A cohort study was conducted among 32,566 patients who received at least 1 yr of HD at the Fresenius Medical Corporation dialysis centers during 1996 to 1997. The outcome measure was all-cause mortality through mid-1998. A total of 19 demographic, comorbidity, and laboratory characteristics were available. By proportional hazards analysis, no adverse effect on 2-year survival was found for baseline iron dose over 6 mo of < or = 1000 mg, but statistically significant elevated mortality was demonstrated for iron doses >1000 mg to 1800 mg (adjusted hazards ratio [HR] = 1.09; 95% confidence interval [CI], 1.01 to 1.17) and >1800 mg (adjusted HR = 1.18; 95% CI, 1.09 to 1.27). However, fitting multivariable models that appropriately account for time-varying measures of iron administration as well as other fixed and time-varying measures of morbidity, the authors found no statistically significant association between any level of iron administration and mortality. This study suggests that previously observed associations between iron administration and higher mortality may have been confounded, and it provides cautious support for the safety of the judicious administration of cumulative iron doses >1000 mg over 6 mo if needed to maintain target hemoglobin levels among patients treated with maintenance HD.

Adolescent↗

PubMed2003

Causal logistic models for non-compliance under randomized treatment with univariate binary response.

We propose a method for estimating the marginal causal log-odds ratio for binary outcomes under treatment non-compliance in placebo-randomized trials. This estimation method is a marginal alternative to the causal logistic approach by Nagelkerke et al. (2000) that conditions on partially unknown compliance (that is, adherence to treatment) status, and also differs from previous approaches that estimate risk differences or ratios in subgroups defined by compliance status. The marginal causal method proposed in this paper is based on an extension of Robins' G-estimation approach for fitting linear or log-linear structural nested models to a logistic model. Comparing the marginal and conditional causal log-odds ratio estimates provides a way of assessing the magnitude of unmeasured confounding of the treatment effect due to treatment non-adherence. More specifically, we show through simulations that under weak confounding, the conditional and marginal procedures yield similar estimates, whereas under stronger confounding, they behave differently in terms of bias and confidence interval coverage. The parametric structures that represent such confounding are not identifiable. Hence, the proof of consistency of causal estimators and corresponding simulations are based on two different models that fully identify the causal effects being estimated. These models differ in the way that compliance is related to potential outcomes, and thus differ in the way that the causal effect is identified. The simulations also show that the proposed marginal causal estimation approach performs well in terms of bias under the different levels of confounding due to non-adherence and under different causal logistic models. We also provide results from the analyses of two data sets further showing how a comparison of the marginal and conditional estimators can help evaluate the magnitude of confounding due to non-adherence.

Confounding Factors, Epidemiologic↗

PubMed2003

Predictors of successful arteriovenous fistula maturation.

BACKGROUND: Understanding the factors associated with successful arteriovenous fistula (AVF) maturation may provide an opportunity to improve vascular access outcomes. METHODS: This prospective cohort study enrolled 348 hemodialysis patients receiving an AVF and followed them until ascertainment of successful AVF maturation. Multivariable logistic regression was used to develop (1) explanatory models of factors associated with AVF success and (2) models for predicting success based on sociodemographic and comorbidity profiles. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminative ability of our predictive model. Predictive probabilities of AVF maturation under the assumption of optimal surgical technique defined by explanatory models were calculated. RESULTS: A total of 55.5% of AVFs successfully matured. A history of stroke or transient ischemic attack, increasing age, and dependence on dialysis at the time of access placement were associated with lower probabilities of maturation. Of potentially modifiable variables, maturation was associated with greater intraoperative doses of heparin, use of large-diameter veins, and mean arterial pressure of 85 mm Hg or greater. Using optimal surgical technique, the probability of successful AVF maturation would have been as high as 84%. A predictive logistic regression model had moderate ability to predict AVF maturation under optimal surgical therapy with an area under the ROC curve of 0.69. CONCLUSION: Surgical technique potentially may be modified to yield a greater probability of successful AVF maturation. Predictive probabilities of successful AVF maturation under optimal surgical technique reinforce the view that functioning AVFs can be achieved in a large proportion of hemodialysis patients, consistent with experience in selected regions of the United States and abroad.

Adult↗

PubMed2003

Association of decreased quality of life and erectile dysfunction in hemodialysis patients.

BACKGROUND: Quality of life in hemodialysis patients has been associated with treatment outcomes. We explored the impact of erectile dysfunction on quality of life in a cohort of hemodialysis subjects. METHODS: A random sample of 302 Philadelphia area hemodialysis (HD) subjects was enrolled using a cross-sectional design. Subjects completed a self-administered questionnaire including items on sexual function, past medical history, and quality of life. Linear regression (accounting for sampling design by weighted estimation methods) was used to examine the associations between various measures of quality of life (the dependent variables) and erectile dysfunction (ED) and other variables (the predictor variables). RESULTS: We found the emotional domains of the SF-36, a multi-purpose, short-form health survey with 36 questions, to be more profoundly associated with ED than the physical domains. Using the physical and mental components of the SF-12, a new 12-item short form health survey as predictors of ED, only the mental composite score (MCS) was statistically significant after adjusting for age and diabetes (P = 0.008). Subjects with ED had significantly lower quality of life mean scores. In particular, ED was associated with poorer social interaction (mean score difference, -10.3, adjusted P < 0.001), decreased emotional well-being (-12.9, adjusted P = 0.005), more role limitations due to emotional problems (-22.9, adjusted P = 0.01), and poorer social function (-17.8, P = 0.001). CONCLUSION: Recent advances in therapies for ED warrant that the diagnosis and treatment of erectile dysfunction be included in the global health assessment by the nephrologists and primary care providers of patients with renal insufficiency, as it may improve the quality of life of patients.

Adult↗

PubMed2003

Determinants of successful synthetic hemodialysis vascular access graft placement.

OBJECTIVE: Synthetic vascular grafts, the most common type of permanent dialysis graft used in the United States, are associated with great morbidity and expense. In this cohort study of patients undergoing hemodialysis and receiving a new synthetic vascular graft, detailed intraoperative procedural data were examined as predictors of graft dysfunction and failure. METHODS: A prospective cohort study of patients receiving hemodialysis who had undergone synthetic (polytetrafluoroethylene) graft placement over 4(1/2) years were followed up until either the graft was no longer usable, kidney transplantation was performed, the patient died, or the study ended. The principal methods of analysis used were the Kaplan-Meier method, to compute survival function for primary and secondary graft patency, and Cox proportional hazards regression, to model associations between predictor variables and graft failure. RESULTS: Of 284 patients enrolled in the study, 172 patients (61%) had at least one graft-related event, ie, temporary graft dysfunction or graft failure, during follow-up. Three-year cumulative graft survival was 54% (95% confidence interval, 45%-62%). Using proportional hazards analysis, history of claudication (rate ratio [RR], 2.14 [range, 0.97-4.73]; P =.06), number of previous permanent grafts (1 graft: RR, 1.49 [range, 0.88-2.51]; 2 or more grafts: RR, 2.85 [range, 1.43-5.69]; P =.01), dialysis dependency at surgery (RR, 2.96 [range, 1.23-7.12]; P =.02), and use of arterial clamps in construction of the graft (RR, 2.32 [range, 1.14-4.73]; P =.02) were associated with lower survival, even after accounting for medical history. Type of graft material, ie, Gore-Tex versus other material (RR, 0.28 [range, 0.16-0.50]; P <.01) and use of the axillary vein (RR, 0.61 [range, 0.36- 1.02]; P =.06) for the access site were associated with a lower rate of graft failure. Similar results were found with Poisson analysis of all graft-related events. In addition, acute arterial anastomosis, ie, arterial angle less than 90 degrees (RR, 0.63 [range, 0.45-0.91]; P =.01) and use of the brachial artery versus the radial artery (RR, 0.54 [range, 0.33-0.54]; P =.01) were associated with a lower rate of graft-related events. CONCLUSION: These findings suggest possible areas for intervention to improve synthetic vascular graft outcome.

Aged↗

PubMed2003

The Chronic Renal Insufficiency Cohort (CRIC) Study: Design and Methods.

Insights into end-stage renal disease have emerged from many investigations but less is known about the epidemiology of chronic renal insufficiency (CRI) and its relationship to cardiovascular disease (CVD). The Chronic Renal Insufficiency Cohort (CRIC) Study was established to examine risk factors for progression of CRI and CVD among CRI patients and develop models to identify high-risk subgroups, informing future treatment trials, and increasing application of preventive therapies. CRIC will enroll approximately 3000 individuals at seven sites and follow participants for up to 5 yr. CRIC will include a racially and ethnically diverse group of adults aged 21 to 74 yr with a broad spectrum of renal disease severity, half of whom have diagnosed diabetes mellitus. CRIC will exclude subjects with polycystic kidney disease and those on active immunosuppression for glomerulonephritis. Subjects will undergo extensive clinical evaluation at baseline and at annual clinic visits and via telephone at 6 mo intervals. Data on quality of life, dietary assessment, physical activity, health behaviors, depression, cognitive function, health care resource utilization, as well as blood and urine specimens will be collected annually. (125)I-iothalamate clearances and CVD evaluations including a 12-lead surface electrocardiogram, an echocardiogram, and coronary electron beam or spiral CT will be performed serially. Analyses planned in CRIC will provide important information on potential risk factors for progressive CRI and CVD. Insights from CRIC should lead to the formulation of hypotheses regarding therapy that will serve as the basis for targeted interventional trials focused on reducing the burden of CRI and CVD.

Adult↗

PubMed2002

Iron administration and clinical outcomes in hemodialysis patients.

To evaluate the impact of parenteral iron administration on the survival and rate of hospitalization of US hemodialysis patients, a nonconcurrent cohort study of 10,169 hemodialysis patients in the United States in 1994 was conducted. The main outcome measures were patient survival and rate of hospitalization. After adjusting for 23 demographic and comorbidity characteristics among 5833 patients included in multivariable analysis, bills for 10 vials showed a statistically significant elevated rate of death (adjusted RR = 1.11; 95% CI, 1.00 to 1.24; P = 0.05). Bills for 10 vials showed statistically significant elevated risk (adjusted RR = 1.12; 95% CI, 1.01 to 1.25; P = 0.03). Prescribing iron in quantities of 10 vials (1000 mg) of iron dextran over a period of 6 mo.

Cohort Studies↗

PubMedDate not supplied

The effect of depressive symptoms and optimism on the risk of spontaneous abortion among innercity women.

BACKGROUND: The role of depressive symptoms and optimism on the risk of spontaneous abortion has not been well examined. Prior studies have documented that emotional stress can affect immune and endocrine function, which may in turn influence fertilization, implantation, embryogenesis, and successful fetal growth. METHODS: We enrolled pregnant women coming to the emergency department at the Hospital of the University of Pennsylvania from January 1999 through August 2001 to examine the role of depressive symptoms and optimism on spontaneous abortion. Cases were women who experienced a spontaneous abortion during the follow-up period (n = 174), and controls were women who maintained their pregnancy through 22 weeks (n = 798). Baseline interviews collected measures of depressive symptoms, using the Center for Epidemiologic Studies Depression Scale (CES-D) and optimism using the Life Oriented Test-Revised (LOT-R). RESULTS: We did not find a significant, prospective relationship between depressive symptoms or optimism and the risk of spontaneous abortion in our specific study population. CONCLUSIONS: The impact of depressive symptoms and optimism on pregnancy outcomes should be examined further in other populations.

Abortion, Spontaneous↗