Clinical data collection was done between 2003 and 2007 for all the 4,434 subjects who were treated in State of Maryland inpatient facilities. Medical records were reviewed to verify DSM diagnoses, co-morbid diseases, smoking status, family history of medical disorders, and severity of illness as well as to collect data on health indices such as height, weight, lipids, glucose and blood pressures. In addition, substance use data was collected using a standardized approach that included data retrieval from DSM diagnoses, urine toxicology data, substance use intake forms and nursing admission notes. All data was collected in the same way. Substance users were defined as subjects with frequent or regular use (more than occasional use), having substance abuse or dependence. Occasional, light and infrequent use were not included, as we wanted to determine the impact of significant drug use on mortality. The following substances identified by name or corresponding street name: alcohol, cannabis, cocaine, heroin, hallucinogens (Lysergic acid diethylamide (LSD), psilocybin/mushrooms and 3,4-methylenedioxy-N-methylamphetamine (MDMA), phencyclidine (PCP), amphetamines and inhalants. Smokers were defined as subjects who ever smoked. Smokers were further categorized as subjects who smoked more than 1 pack daily, less than 1 pack daily or unknown amount.
