Temporal trends in psychotic symptoms: Repeated cross-sectional surveys of the population in England 2000-14

Abstract

Background: The number of antipsychotic prescriptions dispensed annually in England has increased substantially over the past decade. It is not known whether this is due to changes in prescribing practices, or an increase in the prevalence of psychosis. To our knowledge, no previous studies have investigated temporal trends in prevalence of psychotic symptoms in non-clinical populations.

Methods: We used data from the nationally representative Adult Psychiatric Morbidity Surveys 2000, 2007 and 2014 to (1) test whether the prevalence of psychotic symptoms increased between 2000 and 2014; (2) compare prevalence of psychotic symptoms to the prevalence of being prescribed antipsychotic medication; and (3) identify correlates of experiencing psychotic symptoms.

Results: There was a small increase in the prevalence of psychotic symptoms in 2014 compared to 2000 (prevalence in 2000 5.6%, 95% confidence intervals (CI) 5.1% to 6.2%; prevalence in 2014 6.8%, 95% CI 6.1% - 7.6%). This corresponded to an adjusted odds ratio of 1.2 (95% CI 1.02-1.40, p=0.026) for experiencing psychotic symptoms in 2014 compared to 2007. By comparison, antipsychotic medication use doubled over this period (prevalence in 2000 0.6%, 95% CI 0.4%-0.7%; prevalence in 2014 1.2% 95% CI 0.9%-1.5%; aOR 2.22 (1.52-3.25) p<0.001). Correlates of reporting psychotic symptoms included ethnic minority identity, younger age, lower social class, alcohol and cannabis use, and any psychiatric diagnosis.

Conclusions: While the rates of antipsychotic prescription doubled between 2000 and 2014, the odds of having psychotic symptoms rose only slightly. The reasons for this warrant further investigation.

Keywords: Prevalence; Psychosis; Psychotic symptoms; Temporal trends.