The impact of co-morbidity on GPs' pharmacological treatment decisions for patients with an anxiety disorder

Background. Co-morbidity may influence GPs' treatment decisions for patients with anxiety. However, knowledge about differences in the pharmacological treatment of anxiety disorders in patients with and without co-morbidity is lacking. Objective. To compare GPs' pharmacological treatment patterns for anxiety in patients with and without co-morbidity. Methods. Data were extracted from computerized medical records of 77 general practices participating in the Dutch National Information Network of General Practice (LINH). We used diagnosis and prescription data of patients, aged 18–65 years, with a newly diagnosed anxiety disorder (n = 4604). A mixed model technique was used to determine if there was a difference in the pharmacological treatment of anxiety with and without co-morbidity. Results. During the year after diagnosing anxiety, anxious patients who also suffered from chronic somatic morbidity or social problems were prescribed more benzodiazepines (effect size [ES] = 0.44, 95% confidence interval [CI] = 0.16–0.72 and ES = 0.67, 95% CI = 0.22–1.25, respectively) but no more antidepressants than patients with anxiety only. Compared to patients with a single diagnosis of anxiety, anxious patients who suffered simultaneously from other psychiatric conditions received twice as many antidepressant prescriptions (ES = 2.07, 95% CI = 1.89–2.56) as well as twice as many benzodiazepine prescriptions (ES = 1.98, 95% CI = 1.84–2.60) during the year after diagnosing anxiety. For all subgroups, the prescription rate of benzodiazepines remained high throughout the year after diagnosing anxiety. Conclusion. Our results indicate that psychiatric co-morbidity in anxious patients leads to higher prescription levels of both antidepressants and benzodiazepines. Chronic somatic co-morbidity and co-morbid social problems also lead to higher prescription levels of benzodiazepines, but does not seem to influence GPs' prescribing of antidepressants. The prescription pattern of benzodiazepines was inconsistent with guideline recommendations.