Modelling disease frequency measures in schizophrenia epidemiology

Saha, Sukanta, Barendregt, Jan J., Vos, Theo, Whiteford, Harvey and McGrath, John (2008) Modelling disease frequency measures in schizophrenia epidemiology. Schizophrenia Research, 104 1-3: 246-254. doi:10.1016/j.schres.2008.05.022


Author Saha, Sukanta
Barendregt, Jan J.
Vos, Theo
Whiteford, Harvey
McGrath, John
Title Modelling disease frequency measures in schizophrenia epidemiology
Journal name Schizophrenia Research   Check publisher's open access policy
ISSN 0920-9964
Publication date 2008-09-01
Sub-type Article (original research)
DOI 10.1016/j.schres.2008.05.022
Volume 104
Issue 1-3
Start page 246
End page 254
Total pages 9
Place of publication Amsterdam, Netherlands
Publisher Elsevier BV
Collection year 2009
Language eng
Subject C1
920209 Mental Health Services
111714 Mental Health
Formatted abstract
Background
Recent systematic reviews have compiled estimates related to the incidence, prevalence and mortality associated with schizophrenia. The aims of this study were (a) to model various frequency measures, (b) to examine the consistency of the published versus the modelled estimates, and (c) to explore the relative change in prevalence estimates after adjustments were made to incidence, remission, and mortality estimates.

Methods
We identified studies that provided matched incidence and prevalence estimates. We applied the DisMod software program to model incidence from observed prevalence estimates and vice versa. The accuracy of the modelled data was compared to the published data using Mann–Whitney Signed Rank tests. Finally, we conducted several ‘thought experiments’ to explore the impact of changing the incidence, remission, and mortality rates on prevalence estimates.

Results
We identified 24 matched-pairs of incidence and prevalence estimates. The distributions of modelled versus published estimates were significantly different. In 20 pairs, DisMod calculated modelled prevalence estimates that were higher than published estimates, while modelled incidence estimates were lower than published estimates in 21 pairs. In the majority of pairs, the difference between published and modelled estimates was greater than 50%. With respect to the ‘thought experiments’, a 25% reduction in mortality was associated with a 5–7% increase in prevalence, while 25% reduction in incidence or remission rates resulted in 18–23% and 1.2–2.4% decrease in prevalence estimates, respectively.

Conclusion
The consistency between published incidence and prevalence estimates of schizophrenia is poor. Models can help interrogate these inconsistencies and provide insights into the dynamics of schizophrenia epidemiology.
Keyword Incidence
Prevalence
Schizophrenia
Mortality
Remission
Q-Index Code C1
Q-Index Status Confirmed Code

 
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Created: Fri, 20 Mar 2009, 19:00:59 EST by Carmel Meir on behalf of School of Public Health