The natural course of schizophrenia: progressive deterioration, amelioration or both?

Background: It is disputed whether the course of schizophrenia
is characterized by a progressive deterioration, or a progressive
amelioration. Furthermore, it has been recently suggested that progression for the collective is actually attributable to a homogeneous group of patients who are frail and so have the propensity to deteriorate. The current study explores the different possible course patterns of schizophrenia in a national population based cohort.
Methods: All first admissions for schizophrenia in Israel from
1978 to 1992 and their subsequent readmissions were followed in
the National Psychiatric Case Registry (n=11,739), which is a
national population listing of all psychiatric hospitalizations in
Israel. Two recurrent Cox proportional hazards models were conducted with and without a frailty parameter that accounts for
heterogeneity, followed by an examination of readmission patterns.
Results: The frailty model performed better than the Cox model
as the addition of the frailty parameter incremented variance
explained by 12% and the heterogeneity estimate was substantial
(variance of random effect=0.794; c2
=41971.15, df=9003, pb.001). Examination of patients with at least ten years of follow up (n=3798), revealed that approximately three-quarters of the patients were admitted to hospital less over time. Most of the remaining patients showed an increasing readmission rate and a few patients were consistently hospitalized.
Conclusions: A majority of patients systematically follow a
course of progressive amelioration, a substantial number deteriorateover time and a minority is consistently hospitalized.