NON-RESPONSE AND INFORMATION BIAS IN POPULATION-BASED PSYCHIATRIC RESEARCH, ACTA UNIVERSITATIS OULUENSIS D Medica 1049

Study samples in medical research are selected according to the objectives of the studies.\nResearchers seek to collect data as extensively and reliably as possible. In practice, however, data\nare often missing or may be incorrect. This thesis covers some of the problems concerning missing\ndata and data collection in psychiatric research. Methods for adjusting for missing data and for\nevaluating the reliability of data are presented.\nThe data originate from the Northern Finland 1966 Birth Cohort (N = 12058). This study\nexplored how participation in an epidemiologic study that includes questionnaires and a clinical\nexamination is affected by mental health (N = 11540), and whether non-participants experience\nmore severe clinical symptoms than participants in a psychiatric field study (N = 145) among\nsubjects with a psychosis. Inverse probability weighting (IPW) was used to adjust for nonparticipation\nin comparisons of brain volumes between schizophrenia and control groups. The\nprecision of self-reported medication use was also explored (N = 7625).\nIn an epidemiologic study of all cohort members, subjects with a psychiatric disorder\nparticipated less actively than those without one. In the psychiatric field study, non participants\nwere more often patients with schizophrenia than other psychoses. The psychiatric symptoms of\nnon-participants were more severe and they needed more hospital care than participants. The use\nof IPW led to higher estimates of cerebrospinal fluid volume and lower estimates of grey and white\nmatter volumes in schizophrenia patients, and increased the statistical significance of the\ndifferences in brain volume estimates between the schizophrenia and control groups. The\nprecision of self-reported data on psychoactive medication use was substantial.\nDue to non-participation, the true prevalence of psychiatric disorders is probably higher than\nthe prevalence estimates from field studies that are based on data provided by participants only. In\norder to reflect the true differences in the target population, weighting methods can be used to\nimprove estimates affected by non-participation. Regarding psychoactive medication use, data\ncollected by postal questionnaire can be assumed accurate enough for study purposes. However,\nit may underestimate the prevalence of medication use due to non-participation.

ISBN-10:
978-951-42-6156-5
Kieli:
eng.
Sivumäärä:
168 s.
Tekijät:
Haapea Marianne
Tuotekoodi 013958
20,00 €