Deaths observed in Medicare beneficiaries: average attributable fraction and its longitudinal extension for many diseases.

Calculating the longitudinal extension of the average attributable fraction (LE-AAF) for many risk factors (RFs) requires a two-stage computational process using only those combinations of RFs observed in the dataset. We first screen candidates RFs in a Cox Model, and assuming piecewise constant hazards, use pooled logistic regression to model the probability of death as a function of combinations of selected RFs. We average the iterative differencing of the attributable fractions calculated for all overlapping subsets of co-occurring RFs to obtain a LE-AAF for each RF that is additive and symmetrical. We illustrate by partitioning the additive proportions of death from 10 different groupings of acute and chronic diseases, on a national sample of older persons from the US (Medicare Beneficiary Survey) over a 4-year period and compare with results reported by the National Center for Healthcare Statistics. We conclude that careful screening of RFs with analysis restricted to extant combinations greatly reduces computational burden. LE-AAF accounted for a cumulative total of 66% of the deaths in our sample, compared with the 83% accounted for by the National Center for Healthcare Statistics.

Pathological gambling among cocaine-dependent outpatients.

OBJECTIVE: The authors investigated the occurrence of pathological gambling among cocaine-dependent outpatients, its influence on short-term outcome of treatment, and comparative characteristics of patients with and without pathological gambling. METHOD: The subjects were 313 cocaine-dependent (200 also opiate-dependent) outpatients in clinical trials of medication for cocaine dependence. Pathological gambling (DSM-III-R criteria) was assessed with the Diagnostic Interview Schedule, and sociodemographic and socioeconomic characteristics were determined with the Addiction Severity Index. Outcome was defined as time in treatment (proportion of maximum scheduled time) and proportion of cocaine-positive urine samples during treatment. RESULTS: Pathological gambling had a lifetime occurrence rate of 8.0% and a current (past month) occurrence of 3.8%. Onset preceded the onset of cocaine dependence in 72.0% of the patients (and preceded onset of opiate dependence in 44.4%). Patients with pathological gambling (lifetime or current) did not differ significantly from other patients in length of treatment or proportion of cocaine-positive urine samples. Those with lifetime pathological gambling were significantly more likely to have tobacco dependence (84.0% versus 61.1%) and antisocial personality disorder (56.0% versus 19.8%), to be unemployed (84.0% versus 49.3%), to have recently engaged in illegal activity for profit (64.0% versus 38.5%), and to have been incarcerated (62.5% versus 33.9%). CONCLUSIONS: Pathological gambling is substantially more prevalent among cocaine-dependent outpatients than in the general population. Patients with pathological gambling differ from other cocaine-dependent outpatients in some sociodemographic characteristics but not in short-term outcome of treatment for cocaine dependence.

Changes in cigarette smoking not observed following repeated cocaine self-administration.

Acute administration of some psychoactive drugs (e.g., cocaine, heroin, methadone d-amphetamine) has been found to increase spontaneous cigarette smoking for 1-3 hr, but the effects of chronic drug administration have not been systematically studied. Computerized cigarette dispensers were used to study the effects of multiple daily cocaine administrations on cigarette smoking. Participants were 8 (5 male) cocaine-dependent cigarette smokers who resided on a closed clinical research ward and smoked an average of 16.7 cigarettes per day during the week prior to starting the study. During test sessions on Monday, Wednesday, and Friday of each week, participants could obtain either cocaine (25 mg i.v.) on 2 days or saline (1 ml i.v.) on the other day, 3 times per day at 2-hr intervals under double-blind conditions. The number of cigarettes dispensed during study days was analyzed in 2-hr increments. No significant cocaine effect was found. These findings fail to show a change in the number of cigarettes smoked after chronic cocaine self-administration over time intervals longer than 1-3 hr.

Cardiac deceleration and accuracy of performance: recalculation of standard score transform.

In two previous studies the standard score transform used was based on a standard deviation derived from the mean standard deviations of the raw data in the six classifications employed in the studies rather than on one based on the entire set of raw scores as is the more common practice. The data were reanalyzed using the latter basis and major findings were confirmed. Some of the minor findings, however, were changed. These changes are pointed out and discussed where they occurred.

An analysis of the relationship between cardiac deceleration and correct performance under conditions of constant task difficulty.

Previous analyses of the relationship between cardiac deceleration and correct performance suffered from a confounding of task difficulty with performance accuracy. The present analysis indicates that the relationship between these variables still holds and is, in fact, more general under conditions which control difficulty of the task at a constant level.

Cardiac deceleration as an indicator of correct performance.

A within-subjects experiment involving 10 subjects was performed to examine the relationship between the accuracy of judgment of position and cardiac deceleration. The results supported the hypothesis that accurate (correct) performance is accompanied by greater cardiac deceleration than inaccurate performance for those subjects (9 out of 10) who exhibited cardiac deceleration to stimulus onset. The data indicated, however, that the relationship varied with time. Part of this variability appears related to the initial exploratory behavior in which subjects engaged and later reported during the post-experiment interview.