The causal effect of health insurance on utilization and outcomes in adults: a systematic review of US studies.

BACKGROUND: No current consensus exists on the causal effect of gaining or losing health insurance on health care utilization and health outcomes. OBJECTIVE: To systemically search and review available evidence of estimated causal effects of health insurance on health care utilization and/or health outcomes among nonelderly adults in the United States. RESEARCH DESIGN: A systematic search of 3 electronic databases (PubMed, JSTOR, EconLit) was performed. To be included in the review, studies had to have a publication date after 1991; a population of nonelderly adults; analyses comparing an uninsured group to an appropriate control group; and 1 of 3 study designs that account for potential reverse causality and provide estimates of causal effects (longitudinal cohort, instrumental variable analysis, or quasi-experimental design). RESULTS: A total of 9701 studies, including duplicates, were primarily screened. Fourteen studies fulfilled the criteria to be included in this review-4 longitudinal cohort studies using standard regression or fixed effects analysis, 5 longitudinal cohort studies using instrumental variable regression analysis, and 5 quasi-experimental studies. CONCLUSIONS: Results of our review of empirical studies that estimate causal relationships between health insurance and health care utilization and/or health outcomes consistently show that health insurance increases utilization and improves health. Specifically, health insurance had substantial effects on the use of physician services, preventive services, self-reported health status, and mortality conditional on injury and disease. These results both confirm and contradict comparable results from the RAND Health Insurance Experiment, the gold standard on relationships between health insurance, utilization, and health.

Fluorodeoxyglucose uptake of primary non-small cell lung cancer at positron emission tomography: new contrary data on prognostic role.

PURPOSE: This prospective study evaluated the prognostic significance of (18)F-fluorodeoxyglucose ((18)F-FDG) uptake in primary non-small cell lung cancer (NSCLC) at positron emission tomography, in a carefully staged population, while correcting for partial volume effects. EXPERIMENTAL DESIGN: Two hundred eight potentially resectable NSCLC patients were referred for FDG positron emission tomography staging after thoracic computed tomography. Each tumor stage was confirmed surgically, or for some stage IV tumors by additional imaging. The tumor maximum pixel-standardized uptake value (maxSUV) and the maxSUV partial volume corrected for lesion size (PVCmaxSUV) were compared with overall survival and disease-free survival using Cox proportional hazards regression. RESULTS: Stage distribution: stage I, 36%; stage II, 15%; stage III, 30%; stage IV, 19%. Patients were followed for a median of 33.6 months, with 90 deaths from NSCLC (median survival for all stages, 43.3 months). With respect to overall survival, the most significant cutoff value for both maxSUV and PVCmaxSUV was 7. MaxSUV > or =7 was significantly associated with an increased risk of death from NSCLC in univariable analysis, whereas PVCmaxSUV > or =7 was only marginally associated. However, in multivariable analyses, neither maxSUV > or =7 nor PVCmaxSUV > or =7 provided significant additional prognostic information over stage, tumor size, and age. In the 103 patients who underwent surgical resection only, surgical stage, but not maxSUV or PVCmaxSUV, was univariably associated with survival or recurrence. SUV definitions based on lean body mass, body surface area, and plasma glucose correction yielded identical results. CONCLUSIONS: As expected, tumor stage is prognostic in NSCLC. However, tumor FDG uptake does not provide additional prognostic information. This prospective study contradicts prior reports.