We did not include people over 55 years because significant medical co-morbidity may confound the mortality finding. Further, in schizophrenia the average life expectancy is 51–61 years (Newman & Bland 1991; Harris & Barraclough 1998; Colton & Manderscheid, 2006). Finally, the prevalence of substance use in age group >55 years was much less compared to age groups <35 years and 35–55 years.
