Severity of Analgesic Dependence and Medication-overuse Headache

Background and Aims: Medication-overuse headache (MOH) is a common chronic headache caused by overuse of headache analgesics. It has similarities with substance dependence disorders. The treatment of choice for MOH is withdrawal of the offending analgesics. Behavioral brief intervention treatment using methods adapted from substance misuse settings is effective. Here we investigate the severity of analgesics dependence in MOH using the Severity of Dependence Scale (SDS), validate the SDS score against formal substance dependence diagnosis based on the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) and examine whether the SDS predicts successful withdrawal. Methods: Representative recruitment from the general population; 60 MOH patients, 15 chronic headache patients without medication overuse and 25 population controls. Headaches were diagnosed using the International Classification of Headache Disorders, medication use was assessed and substance dependence classified according to the DSM-IV. The SDS was scored by interviewers blinded to patient group. Descriptive statistics were used and validity of the SDS score assessed against a substance dependence diagnosis using ROC analysis. Results: Sixty-two percent of MOH patients overused simple analgesics, 38% centrally acting analgesics (codeine, opiates, triptans). Fifty percent of MOH patients were classified as DSM-IV substance dependent. Centrally active medication and high SDS scores were associated with higher proportions of dependence. ROC analysis showed SDS scores accurately identified dependence (area under curve 88%). Lower SDS scores were associated with successful withdrawal (P = 0.004). Conclusions: MOH has characteristics of substance dependence which should be taken into account when choosing treatment strategy.