Delayed initiation of subcutaneous insulin therapy after failure of oral glucose-lowering agents in patients with Type 2 diabetes: a population-based analysis in the UK.

AIMS: The aim of this retrospective cohort study was to estimate the time to insulin initiation in patients with Type 2 diabetes inadequately controlled on oral glucose-lowering agents (OGLAs). METHODS: Insulin-naïve patients failing on OGLAs were identified from The Health Improvement Network database, which collects records from general practices throughout the UK. Patients were included if they were aged > or = 40 years, had concomitant prescriptions for > or = 2 OGLAs, and > or = 1 year of available records prior to the first occurrence of HbA(1c) > or = 8.0% after > or = 90 days of OGLA polytherapy at > or = 50% of maximum recommended dosages. RESULTS: A total of 2501 eligible patients with Type 2 diabetes who had an HbA(1c) above the OGLA failure threshold of > or = 8.0% were identified (54.0% male; 30.9% aged 60-69 years). It was estimated that if all the eligible patients were followed for 5 years, 25% would initiate insulin within 1.8 years of OGLA failure (95% CI 1.6-2.0), and 50% within 4.9 years (95% CI 4.6-5.8). The presence of diabetes-related complications had no substantial impact on the time to insulin initiation. CONCLUSIONS: This study found that 25% of patients with Type 2 diabetes had insulin initiation delayed for at least 1.8 years, and 50% of patients delayed starting insulin for almost 5 years after failure of glycaemic control with OGLA polytherapy, even in the presence of diabetes-related complications. Interventions that reduce this delay to insulin initiation are required to help achieve and maintain recommended glycaemic targets in patients with Type 2 diabetes.

The effect of hospital volume on the in-hospital complication rate in knee replacement patients.

OBJECTIVE: To examine the effect of hospital volume on in-hospital surgical outcomes for knee replacement using six years of Medicare claims data. DATA SOURCES/STUDY SETTING: The data include inpatient claims for a 100 percent sample of Medicare patients who underwent primary knee replacement during 1985-1990. We supplemented these data with information from HCFA's denominator files, the Area Resource File, and the American Hospital Association survey files. STUDY DESIGN: We estimated the probability that a patient has an in-hospital complication in the initial hospitalization for the first primary knee replacement, using a Logit model, for three definitions of complication. The models controlled for hospital volume, other hospital characteristics, patient demographics, and patient health status. We tested for the endogeneity of hospital volume. DATA COLLECTION/EXTRACTION METHODS: A panel of two orthopaedic surgeons and two internists reviewed diagnosis codes to determine whether a complication was likely, possible, or due to anemia. After removing the few observations with bad or missing data, the final population has 295,473 observations. PRINCIPAL FINDINGS: The probability of a likely in-hospital complication declines rapidly from 53 through 107 operations per year, then levels off. Statistical tests imply that hospital volume is exogenous in this patient-level data. Complication rates increased steadily through the study period. Although obesity appeared to lower the probability of a complication, a counterintuitive result, further investigation revealed this to be an artifact of the claims data limit of listing no more than five diagnoses. Controlling for this restriction reversed the effect of obesity. CONCLUSIONS: Rather than uncontrolled expansion of knee surgery to small hospitals, decentralization to regional centers where at least about 50, and preferably about 100, operations per year are assured appears to be the optimal policy to reduce in-hospital complications.

Dilution assay statistics.

A parametric method of statistical analysis for dilution assays is developed in detail from first principles of probability and statistics. The method is based on a simple product binomial model for the experiment and produces an estimate for the concentration of target entities, a confidence interval for this concentration, and an indicator of the quality of the assay called the p value for goodness of fit. The procedure is illustrated with data from a virologic quantitative micrococulture assay used to quantify free human immunodeficiency virus in clinical trials. The merits of the procedure versus those of nonparametric methods of estimating the dilution inducing a 50% response rate are discussed. Advantages of the proposed approach include plausibility of the underlying assumptions, ability to assess plausibility of specific experimental outcomes through their likelihood, and plausibility of confidence intervals.