Although not statistically significant, clinically important differences in the median, 2-, 3-, and 4-year survival rates were observed, with a trend in favor of concurrent chemoradiation therapy, suggesting that is the optimal strategy for patients with locally advanced NSCLC.

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BackgroundDouble-adjustment can be used to remove confounding if imbalance exists after propensity score (PS) matching. However, it is not always possible to include all covariates in adjustment. We aimed to find the optimal imbalance threshold for entering covariates into regression.MethodsWe conducted a series of Monte Carlo simulations on virtual populations of 5,000 subjects. We performed PS 1:1 nearest-neighbor matching on each sample. We calculated standardized mean differences across groups to detect any remaining imbalance in the matched samples. We examined 25 thresholds (from 0.01 to 0.25, stepwise 0.01) for considering residual imbalance. The treatment effect was estimated using logistic regression that contained only those covariates considered to be unbalanced by these thresholds.ResultsWe showed that regression adjustment could dramatically remove residual confounding bias when it included all of the covariates with a standardized difference greater than 0.10. The additional benefit was negligible when we also adjusted for covariates with less imbalance. We found that the mean squared error of the estimates was minimized under the same conditions.ConclusionIf covariate balance is not achieved, we recommend reiterating PS modeling until standardized differences below 0.10 are achieved on most covariates. In case of remaining imbalance, a double adjustment might be worth considering.Electronic supplementary materialThe online version of this article (doi:10.1186/s12874-017-0338-0) contains supplementary material, which is available to authorized users.

SUMMARYPurpose: To determine the prevalence of epilepsy in a defined adult population and identify the frequency and principal features of pharmacoresistant epilepsy. Methods: From a population over 15 years of age residing in a medium-sized French city, all patients with epilepsy on June 30, 1995 were identified from multiple sources. Pharmacoresistance was defined as failure to control epilepsy by at least two firstline antiepileptic drugs, with a seizure frequency of at least one per month for 18 months. Collected data were examined by experts in epileptology, and responding patients were reexamined using a standardized diagnostic questionnaire. ILAE definitions and classifications were used. Results: The age-adjusted prevalence of active epilepsy was 5.4 per 1,000 (95% CI: 4.7-6.0) and was higher for males (7.8) than for females ( Prevalence studies provide pertinent epidemiological data for a rational approach to planning health-care provision, as well as providing a basis for hypothesis generation in clinical research or analytical epidemiological studies. Many studies have been performed in the past to determine the prevalence of epilepsy and these have yielded prevalence rates of active epilepsy varing from