Context It has been suggested that attenuated psychotic symptoms (APSs) reported by people who do not have psychotic disorders signal risk for later severe mental illness.
Objective To investigate this suggestion using follow-up assessments of hospitalization for clinical diagnoses of nonaffective psychotic and other psychiatric disorders.
Design Longitudinal cohort study of self-reported APSs with outcome assessment of severe mental illness obtained through linkage with a national hospitalization case registry.
Participants A stratified full probability sample of 4914 persons aged 25 to 34 years who were screened for psychopathology in the 1980s.
Main Outcome Measure Subsequent psychiatric hospitalization was ascertained using the psychiatric hospitalization registry, with a mean follow-up of 24 years.
Results After removing subjects with diagnosable psychotic disorders at baseline, 57.2% of the remaining sample reported at least 1 weak (infrequent) APS and 14.3% reported at least 1 strong (frequent) APS in the year preceding the assessment. Self-reported APSs predicted risk of later hospitalization for nonaffective psychotic disorders, mostly during the 5 years after baseline (adjusted odds ratio = 4.31; 95% CI, 2.21-8.41; positive predictive value = 1.27%; population attributable risk fraction = 33%). Also, APSs increased the risk of later hospitalization for other psychiatric disorders, albeit to a lesser extent (adjusted odds ratio = 2.21; 95% CI, 1.02-4.82).
Conclusions Self-reported APSs signal risk for later nonaffective psychotic disorders but are not clinically useful as predictors. The difference between these population-based data and the high-risk literature in terms of the positive predictive value (1% vs 10%, respectively) and the time window of transition (5 years vs 12 months, respectively) can be attributed to the selective enrichment strategies that produce high-risk samples.