The characteristic pain intensity score ranges from 0 to 100 and is evaluated by calculating the mean of pain intensities reported for current pain status, as well as the worst and the average pain in last 6 months. The disability score (0–100) is based on the mean ratings of how much the pain has interfered in performing activities of daily living, work and social activities in the last 6 months. The disability points are scored 0–3 and are derived from a combination of ranked categories of the number of disability days (the number of days that the respondent was away from usual activities in the last 6 months due to pain) and disability

score. Based on these scores, the respondent’s chronic pain and disability status can then be classified into one of the 5 hierarchical categories of chronic pain/disability: BIBW2992 no pain (Grade 0), low disability and low intensity (Grade I), low disability PD0325901 in vitro and high intensity (Grade II), high disability and moderately limiting intensity (Grade III), high disability and severely limiting intensity (Grade IV) (Von Korff et al 1992). Being a patient-reported measure, the CPGQ is extremely easy to administer, score, and interpret, therefore it requires minimal training. The administrative burden of the CPGQ is less than 10 minutes. Reliability,

validity and responsiveness: CPGQ was originally administered via telephone interviews for patients with back pain, headache, and temporomandibular joint pain. However, subsequent research has expanded its utility in postal surveys in general population and chronic musculoskeletal pain. It was found to have good correlation with the equivalent dimensions of SF-36 questionnaire; highest for pain and least for mental health dimension (convergent validity). Factor analyses demonstrated that all the seven items contributed significantly to the explained variance (> 75%) ( Smith et al 1997). Furthermore, moderate to good internal consistency (Cronbach’s alpha, 0.74 to 0.91) and good test retest reliability has been demonstrated in primary care patients with back pain (weighted kappa –0.81, 95% CI 0.65 to 0.98) (

Smith et al 1997). A study by Elliot et al showed that changes in CPGQ score over a period of time in patients with chronic musculoskeletal pain correlated from significantly with changes in SF-36 scores ( Elliott et al 2000). Responsiveness statistics and minimal clinically important difference (MCID) of the CPGQ have not been reported in the literature. CPGQ is a reliable and valid measure for evaluation of chronic pain in the general population as well as in the primary health care setting. A recent study demonstrated that even though CPGQ was developed prior to the WHO International Classification of Functioning, Disability & Health (ICF), it measures all the ICF outcomes ie, impairment, activity limitation and participation restriction (Dixon et al 2007).