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Dougal Jeffries suggests that the inclusion in the QOF of payments for using the Hospital Anxiety and Depression Scale (HAD), or other measures of severity, will encourage antidepressant prescribing,1 but I think he's wrong.
I can give Dougal evidence that the introduction of these measures is likely to help to rationalise antidepressant prescribing. Anticipating their introduction by 6 months, Southampton City Primary Care Trust agreed to reward practices for measuring the severity of depression, through the Trust's prescribing audit incentive scheme. Participating practices used the HADS depression sub-scale (HAD-D), with all patients they were considering for possible treatment for depression, between December 2005 and April 2006.
The GPs were advised that active intervention should not usually be offered to patients scoring less than 8 out of 21 on the HAD-D (indicating major depressive disorder is unlikely), while patients scoring 8 to 10 out of 21 (indicating possible major depressive disorder) should be followed up, to see if their depression worsened. They were further advised that patients scoring 11 or more (indicating probable major depressive disorder) would be likely to benefit from antidepressants, or referral for counselling or psychological treatment, if this was preferred by doctor or patient. Anonymous data on the number of patients assessed using the HAD-D and the subsequent care provided by participating practitioners were collected from the practices' computer records systems at the end of the 5-month study period by the Trust's pharmaceutical advisors.
Table 1 shows that that the likelihood of being prescribed an antidepressant increased significantly with severity on the HAD-D (χ2 = 17.3, degrees of freedom [df] = 2, P<0.0001). A sizeable minority of patients were referred for psychological treatments in each severity category, with no significant differences between categories (χ2 = 3.73, df = 2, P = 0.155). Note that around 20% of those with probable major depressive disorder were not prescribed antidepressants, while more than 40% of those scoring below the threshold for possible major depressive disorder were treated. Therefore the practitioners did not always follow published guidance, which is not to offer treatment to patients with mild depression.
However, this may have been for a number of reasons. Only the depression sub-scale of the HADS was used in the study, so there was no measure of anxiety symptoms. It is possible that those with lower scores on the HAD-D were prescribed antidepressants for anxiety symptoms, for which they are also licensed. It is also possible that patients with a past history of more severe depression were offered active treatment to prevent recurrence in spite of a currently low severity score. It is also highly likely, given the high level of intervention overall among these patients, that the GPs only measured severity in those patients for whom they were already actively considering treatment, and not for most of those they perceived to be mild cases.
Overall, of 134 new courses of antidepressants recorded in this study, only 18 (13.4%) were for patients with scores below the threshold for possible major depressive disorder, indicating good targeting of antidepressant treatment within this group, in line with guidelines. This may be compared with a previous observational study of practitioner treatment of depression in Southampton, which showed that antidepressants were poorly targeted to those with more severe depression, due to the inaccuracy of practitioner clinical assessment of severity when compared to the HAD-D.2 In the previous study more than 40% of antidepressants were offered to patients with sub-threshold scores compared to around 13% in this study. Measuring severity therefore does seem to improve the targeting of GP antidepressant treatment, which is the aim of the quality indicator.
TK has received fees for speaking at educational events from Pfizer, Lilly, Wyeth and Lundbeck pharmaceuticals. He was a member of the expert advisory group on the mental health indicators for the 2005 Quality and Outcome Framework. He is Chief Investigator on a successful application for pharmaceutical company funding for a larger study of changes in the treatment of depression following the introduction of the severity indicators.