A Population-Based Longitudinal Study of Symptoms and Signs Before the Onset of Psychosis.

Objective: The authors sought to characterize the symptoms of patients later hospitalized for psychotic disorders in primary mental health outpatient settings, and to investigate whether these symptoms can be used to predict later onset of psychotic illness.
Method: This was a population-based historical prospective cohort study using national registers of clinical psychiatric services. The sample (N=114,983) comprised 18- to 21-year-olds serving in the Israeli military and examined in military mental health outpatient clinics across 72 consecutive months.
Results: Overall, 1,092 individuals (0.95%) not diagnosed with a psychotic disorder at the time of examination were hospitalized for nonaffective psychotic disorder up to 9 years after the index examination. A principal components analysis of symptoms presented at index examination found that a symptom cluster of thought disorder, perceptual abnormalities, poor orientation, and suicidality was associated with an increased risk for hospitalization for nonaffective psychotic disorder within 14 days after examination (hazard ratio=45.80, 95% CI=22.87-91.73), 15-111 days after examination, (hazard ratio=19.59, 95% CI=13.08-29.33), 112-365 days after examination (hazard ratio=4.94, 95% CI=2.59-9.40), and 1-3.5 years after examination (hazard ratio=3.42, 95% CI=2.21-5.28), but not for hospitalization 3.5 years or more after examination (hazard ratio=1.57, 95% CI=0.91-2.71). Despite the increased risk, the positive predictive values of this symptom cluster were low, ranging from 0.54% to 1.99%.
Conclusions: In 18- to 21-year-olds, the presence of psychotic symptoms was associated with later hospitalization for a nonaffective psychotic disorder. However, the low positive predictive values of symptoms elicited in primary mental health care settings suggest that symptoms alone are not useful in predicting later hospitalization for nonaffective psychotic disorder.