Patients' beliefs about depression and how they relate to duration of antidepressant treatment. Use of a US measure in a UK primary care population

Background: Patients have a wide range of explanations for their depression and it is not known how these beliefs influence subsequent behaviour and hence outcome. Research question: What are patients' beliefs about depression and do they relate to duration of antidepressant treatment? Design of study: Cross-sectional questionnaire survey. Setting: A general practice in the South of England. 

Methods: All patients prescribed antidepressant medications over a 1-year period were asked to complete a validated questionnaire on beliefs about depression (PDIQ), a current depression and anxiety score (HADS), a measure of compliance with medication (MARS) and a demographic questionnaire. Results from the PDIQ were analysed by exploratory factor analysis. Multiple regressions were used to determine predictors of belief and whether belief predicted duration of medication. 

Results: Two-hundred and eight patients (33%) consented to participate. Factor analysis produced a coherent underlying belief structure, similar to results obtained in the US and related to Leventhals self-regulatory model of illness cognitions. Antidepressant medication was taken for longer by older participants and those with beliefs that antidepressants help, medical illness causes depression, and that depression is chronic. Antidepressant medication was taken for a shorter time by those who were in a stable relationship, or believed herbal remedies or 'clarifying priorities' would help depression. Beliefs accounted for up to 35% of the variability in duration of medication. 

Conclusions: Beliefs do seem to be related to duration of treatment in this cross-sectional study. Longitudinal research is needed to establish cause and effect.