Using routine data to conduct small area health needs assessment through observing trends in demographics, recording of common mental health problems (CMHPs) and sickness certificates: longitudinal analysis of a northern and London locality

<strong>Background</strong> Many practices in the UK have computerised information dating back to the 1990s. These health records provide contemporaneous collected longitudinal data for analysis of health trends and their management in primary care over time. <strong>Objective</strong> This study examines the trends in common mental health problems (CMHPs), prescription of antidepressant, anxiolytics and hypnotics and medical certificates over four years to highlight the strengths and pitfalls in trends analysis using primary care data. <strong>Method</strong> Relevant clinical information for the first six months of each of the calendar years 2004, 2005, 2006 and 2007 were extracted from participating practices in a London locality and in the North. <strong>Results</strong> Between 2004 and 2007 recorded episodes ofCMHPsrose from 33 to 45 per thousand adults in the northern site, and from 19 to 22 in the London site. Prescriptions of antidepressants, anxiolytics and hypnotics rose (from 381.4 to 418 per thousand adults) in the northern site but did not increase in the London site. Medical certificates increased steadily (from 32.7 to 61.6 per thousand adults with a CMHP) in the London site but not in the northern. Recorded episodes of CMHPs and prescriptions of antidepressants, anxiolytics or hypnotics are much higher in the northern site than the London site; the rate of medical certificates per thousand adults with CMHPs in the northern site is more than ten times that in the London site. <strong>Conclusions</strong> Demographics, diagnostic and prescribing data are of high quality in primary care, and they could be used more to understand local health needs and inform commissioning decisions