Delusional infestation and patient adherence to treatment: an observational study

Delusional infestation (DI) is the persistent belief of pathogenic infestation of the skin or body, without objective medical evidence. Treatment for symptoms of delusions can be particularly challenging, especially when patients are difficult to engage and adverse to the possibility of a nonskin disorder. To date there has been no study to evaluate patient adherence to DI treatment.

To assess the adherence of patients with DI to psychotropic and/or dermatological medication.

Sixty-nine consecutive patients with DI receiving treatment from our psychodermatology clinic were identified from a departmental database. Patient adherence to treatment was assessed via medical records, patient letters and a telephone questionnaire.

Eighteen of 69 patients were noncontactable, reducing the sample size to 51. Forty-nine of 51 patients were receiving psychotropic medication (96%). Psychotropic agents included second-generation antipsychotics and antidepressants. Twenty-nine of 49 patients were adherent to psychotropic medication. Secondary nonadherence was reported by 18 of 49 patients. Two patients were nonadherent to psychotropic medication. Adherence to dermatological medication was high (96%).

This is the first study to assess the adherence of patients with DI to treatment. The majority of patients on psychotropic medication were compliant. Secondary nonadherence was mainly due to drug side-effects. The adherence to dermatological medications is high. Thorough counselling of patients with regard to indication, dosage and side-effects of psychotropic agents can improve adherence to medication and is an essential part of the treatment process for DI.