| Data collection method: |
Data have been collected via postal questionnaire. Patients are registered with 24 general practices currently participating in CPRD data collection. The location of these practices depends on the willingness of GPs to support the study. Ideally, however, there will be purposive quota sampling aimed at ensuring a reasonable geographical spread e.g. at least 25% of total list size from each of the South, Midlands and North. We consider this sensible as unemployment rates and patterns of illness behaviour and consulting will vary geographically. However, there is no requirement that the distribution of respondents’ occupations should be nationally representative. Subjects received a questionnaire at baseline and a briefer questionnaire at follow-up (annually for 3 years initially). The age limits have been chosen on the expectation that some subjects will already be retired at baseline, some will retire at follow-up with others deferring retirement, and many will develop retirement plans. No other inclusion or exclusion criteria are envisaged - all patients in the relevant age band from each participating practice were invited to participate for the duration of follow-up. The questionnaire at baseline asked about: 1) current work status; 2) among those in paid work – main occupation, length of service, pattern of work (e.g. salaried vs. piece work, permanent vs. temporary), employer’s size, physical and psychosocial working conditions (e.g. kneeling, climbing, digging, heavy lifting, standing, shift and night work, work demands and support), job satisfaction, conflicts at work, job security, income protection in illness; self-reported ability to cope with work demands); 3) financial status (e.g. contribution to total household income, housing tenure, affordability of consumer durables, pension provision; 4) attitudes to work and retirement – how long the person would like to work, how long they need to work, their intended retirement age; 5) demographic, social and anthropometric data – education and qualifications, marital status, dependants and caring commitments, household composition, height and weight; 6) leisure and social activities; 7) smoking and alcohol history; 8) selected health items: sickness absence in past 12 months; regional pains in past 12 months; Self-Rated Health (SRH); abridged Sleep Problems Scale; Brief Symptom Inventory (BSI) somatising scale; Center for Epidemiologic Studies Depression Scale (CES-D);and the Warwick-Edinburgh Mental Well-being Scale (MWBS); brief items on items on frailty (Fried frailty index) and cognition. The follow-up questionnaire assessed changes from baseline in: 1) job circumstances, with reasons (job loss, new job, job modification, for health-related or other reasons); 2) health (e.g. hospital referrals, new diagnoses, new treatments, new workplace injuries, changes in SRH, BSI, CES-D, MWBS, frailty, cognition); and 3) attitudes towards retirement (including those modified by spouse’s health and employment). The CPRD provides the main source of information on health at baseline and over follow-up. |
