Incidence and cumulative risk of treated schizophrenia in the prenatal determinants of schizophrenia study

The present study uses data from the Prenatal Determinants of Schizophrenia (PDS) Study to derive age- and sex-specific estimates of incidence and cum ulative risk for DSM-IV schizophrenia. Although not designed as an incidenc e study, the PDS Study uses both a well-defined population under continuous followup and DSM-IV diagnoses, The originating cohort mas established in A lameda County, California, during 1959-1967 and yielded 12,094 cohort membe rs followed from 1981 to 1997 during the principal ages at risk for schizop hrenia. Survival analytic techniques showed that schizophrenia incidence ra tes per 10,000 person-gears for men mere 9.4 for ages 15-19; 5.6 for ages 2 0-24; 3.3 for ages 25-29; and 0.9 for ages 30-34, Schizophrenia incidence r ates per 10,000 person-years for women mere 1.6 for ages 15-19; 1.3 for age s 20-24; and 4.1 for ages 25-29, The cumulative risk for schizophrenia by a ge 38 mas 0.93 percent for men and 0.35 percent for women. These estimates of incidence rates and risk mere higher than those in traditional incidence studies but similar to recent findings in other cohorts. Possible explanat ions for the apparently high rates of disorder include chance, design effec ts, and true variation in risk over time and place.