Study should have used deprivation index that is independent of age

Editor—There is a fatal flaw in the objective of the study by Julia Hippisley-Cox and colleagues: the Jarman underprivileged area (UPA(8)) score is used as a proxy measure to determine the effect of deprivation on variations in the outpatient referral rates of general practitioners.1 It is hardly surprising that there is a correlation between the Jarman score and referral rates; the Jarman score was devised specifically to predict workloads in primary care.2 3

The Jarman index included as one of its factors the proportion of elderly people living alone, which correlates strongly with the proportion of elderly people in a population. Indeed, the category of elderly people living alone was given the strongest weighting by general practitioners because they knew that the population of elderly people was the major factor which would influence their workload. It is equally well known that age has a strong influence on referral rates. Elderly people are far more likely than young people to be referred to hospital; this is the reason for the age-cost curve in the national resource allocation formula.4

The fact that the Jarman index correlates with referrals by general practitioners is a statement of the obvious—it confirms that the index measures what it claims to measure. Practices with high Jarman scores will almost certainly have a high proportion of elderly people and therefore have high rates of referral. To claim that this correlation shows a link with social deprivation is to miss the point. The age structure of a population is not an indicator of deprivation, and many of the most deprived practice populations, such as those found in the inner cities, will have …