The validation of the Italian Perceived Disability Scale (IPDS) in chronic daily headache sufferers

The goals of this study were to assess the validity and usefulness of a new scale and to assess disability in a sample of patients with chronic daily headache. Participants were a convenience sample of 61 adult outpatients admitted to the Department of Medical Sciences of the Sant'Andrea Hospital in Rome, between September 2007 and May 2008. Inclusion criteria were, a diagnosis of chronic daily headache (illness duration >5 years). Patients were administered the Beck Hopelessness Scale (BHS), a specific section of the Mini-International Neuropsychiatric Interview (MINI) assessing suicidal intent, the Gotland Male Depression Scale (GMDS), and a scale devised to measure the degree of disability caused by the headache [Italian Perceived Disability Scale (IPDS)]. Analyses indicated that the IPDS had good internal consistency (Cronbach alpha = 0.93; average inter-item correlation = 0.40), and good convergent validity, with moderate to strong associations with measures assessing emotional distress (BHS, r = 0.47; P < 0.0001; GMDS, r = 0.72; P < 0.001). A single-item, logistic regression analysis indicated that the IPDS is able to predict suicide intent (Wald chi(2) = 5.04; P < 0.05) in chronic daily headache patients. The IPDS is a brief instrument that is useful for comparisons with other chronic illnesses, and it may be used both for basic research and clinical applications when screening for comorbidity with emotional distress and disorders.