Recalibrating the Quantitative Relationship Between Duration of Untreated Psychosis and Outcome for Health Service Models

INTRODUCTION: Though influential for models of health care provision, the service-critical issue of the quantitative relationship between duration of untreated psychosis (DUP) and outcome remains poorly understood: is the association between longer DUP and greater impairment distributed uniformly across the range of DUP values encountered, or does it vary with particular gradations of DUP within that range? METHODS: In the Cavan-Monaghan First Episode Psychosis Study, 160 subjects experiencing first episode psychosis (FEP) were evaluated for DUP, premorbid features and severity of negative symptoms as a critical determinant of functional outcome and quality of life. Multiple regression involved age, sex, premorbid intelligence, premorbid social adjustment and quartile split of DUP values to identify, naturalistically, gradations across the days, weeks, months and years of DUP. RESULTS: Across the initial days and weeks of psychosis there was no relationship between DUP and severity of negative symptoms; 3 weeks constituted a temporal threshold beyond which, through to 4 months, longer DUP was associated with greater severity of negative symptoms; beyond 4 months, longer DUP was associated with yet further increases in severity of negative symptoms. These findings at FEP were then juxtaposed with results from two previous studies of DUP quartiles in relation to severity of negative symptoms across periods beyond FEP to 7-year and 20-year follow-ups; all three studies indicated notably similar results. CONCLUSIONS: These relationships indicate that even modest reductions in what would otherwise have been prolonged periods of DUP may be associated with a sustained reduction in the severity of negative symptoms.