An adapted Severity of Dependence Scale is valid for the detection of medication overuse: the Akershus study of chronic headache

Background and objective: Medication overuse headache is a common subtype of chronic headache involving the overuse of simple analgesics, opioids, ergotamine or triptans or combinations of these medications. Medication overuse may worsen the headache and has been described to have many characteristics similar to addiction. The purpose of this study was to validate and optimize the Severity of Dependence Scale (SDS) for use amongst people with chronic headache.

Design/setting: In a cross-sectional epidemiological survey, an age- and gender-stratified sample of 30,000 30- to 44-year-old people were recruited via a posted questionnaire. Those with self-reported chronic headache were interviewed by neurological residents at Akershus University Hospital, Oslo. Headache was classified according to the International Classification of Headache Disorders. Split file methodology was employed for data analysis.

Main outcome measure: Severity of Dependence Scale score in those with and without medication overuse.

Results: Severity of Dependence Scale score was a significant predictor of medication overuse amongst chronic headache patients. Medication overuse could be predicted with sensitivity, specificity, positive and negative predictive values of 0.79, 0.84, 0.84 and 0.79, respectively, in men and 0.76, 0.77, 0.73 and 0.79 in women. Linear regression and factor analysis suggested a redundancy for the SDS question 'Do you think your use of your headache medication was out of control?' Removal of this question improved Chronbach's alpha=0.76.

Conclusion: The SDS is valid for detecting medication overuse and dependency like behaviour amongst people with chronic headache. The adapted version may be used to identify chronic headache patients who may benefit from detoxification.