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.

Venous leg ulcer: incidence and prevalence in the elderly.

BACKGROUND: Venous leg ulcer is a disease most common in those aged 65 years and older. However, the incidence and prevalence have not been well established. OBJECTIVE: Our purpose was to estimate the prevalence and incidence of venous leg ulcers in the elderly. METHODS: We studied the General Practice Research Database, validated our case ascertainment strategy, and estimated the annual prevalence and incidence of venous leg ulcer. RESULTS: The positive predictive value of our ascertainment strategy was 98.3% (95% confidence interval [CI], 90.0, 100.0). The annual prevalence of venous leg ulcer among the elderly was 1.69 (95% CI, 1.65, 1.74). The overall incidence rate was 0.76 (95% CI, 0.71, 0.83) for men and 1.42 (1.35, 1.48) per 100 person-years for women. CONCLUSION: Venous leg ulcer is a significant problem in those aged 65 years and older. As compared with previous studies, because we used medical records from a population of known size, our results are precise and less biased.

Individual patient- versus group-level data meta-regressions for the investigation of treatment effect modifiers: ecological bias rears its ugly head.

When performing a meta-analysis, interest often centres on finding explanations for heterogeneity in the data, rather than on producing a single summary estimate. Such exploratory analyses are frequently undertaken with published, study-level data, using techniques of meta-analytic regression. Our goal was to explore a real-world example for which both published, group-level and individual patient-level data were available, and to compare the substantive conclusions reached by both methods. We studied the benefits of anti-lymphocyte antibody induction therapy among renal transplant patients in five randomized trials, focusing on whether there are subgroups of patients in whom therapy might prove particularly beneficial. Allograft failure within 5 years was the endpoint studied. We used a variety of analytic approaches to the group-level data, including weighted least-squares regression (N=5 studies), logistic regression (N=628, the total number of subjects), and a hierarchical Bayesian approach. We fit logistic regression models to the patient-level data. In the patient-level analysis, we found that treatment was significantly more effective among patients with elevated (20 per cent or more) panel reactive antibodies (PRA) than among patients without elevated PRA. These patients comprise a small (about 15 per cent of patients) subgroup of patients that benefited from therapy. The group-level analyses failed to detect this interaction. We recommend using individual patient data, when feasible, to study patient characteristics, in order to avoid the potential for ecological bias introduced by group-level analyses.