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Methodological pitfalls in early detection studies – the NAPE Lecture 2002

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Friis S, Larsen TK, Melle I, Opjordsmoen S, Johannessen JO, Haahr U, Simonsen E, Rund BR, Vaglum P, McGlashan T. Methodological pitfalls in early detection studies – the NAPE Lecture 2002.

Acta Psychiatr Scand 2003: 107: 3–9. © Blackwell Munksgaard 2003. Objective:

To identify and discuss methodological pitfalls that may help explain why many questions around early detection (ED) and duration of untreated psychosis (DUP) are still unsolved. Method:

This paper concentrates on pitfalls in the following areas: sampling, measurement and data analyses. Results:

The main problems seem to be: Sampling: Referral bias, exclusion of patients, patient refusal, and patients lost to follow-up. Measurement: Reliability, which is particularly cogent for multisite investigations, and validity, which includes: Start of illness, start of psychosis, diagnoses, start of treatment, the relationship between ED and DUP and choice of outcome measures. Data analyses: 

Overlooking threshold effects of DUP, improper control for baseline scores, and lack of control for confounders. Conclusion:

Methodological pitfalls may bias ED studies. Several pitfalls are unavoidable, but proper design and quality assurance can reduce their impact. Researchers ought to identify the pitfalls, and to estimate and discuss their influence.
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Keywords: Confounding factors; early intervention; psychotic disorders; reproducibility of results; research design

Document Type: Research Article

Affiliations: 1: Division of Psychiatry, Ullevål University Hospital, Oslo, Norway, 2: Rogaland Psychiatric Hospital, Stavanger, Norway, 3: Roskilde County Psychiatric Hospital Fjorden, Roskilde, Denmark, 4: Institute of Psychology, University of Oslo, Oslo, Norway, 5: Department of Behavioral Sciences, University of Oslo, Oslo, Norway and 6: Yale Psychiatric Research Institute, Yale University, New Haven, CT, USA

Publication date: January 1, 2003

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