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Quality of life instruments

Skin conditions can have a significant impact on patients’ daily lives.

Physicians and patients often use different criteria when assessing the severity of a medical condition. Disease severity is not only related to physical parameters (e.g. thickness, redness, scaling and area of involvement in the Psoriasis Area Severity Index), but also to psychological and social components.

Recently, health-related quality of life (HRQOL) has emerged as an important component of disease burden and an important part of the clinical assessment. HRQOL is the patients’ evaluation of the effects of their illness and/or treatment on their physical, psychological and social well-being and ability to function. HRQOL assessment is now a standard outcome measure in most clinical research studies. Treatment aims for a decrease in disease severity and an increase in HRQOL. Many instruments have been developed to assess HRQOL. In dermatology, three types of instruments can be used: generic, dermatology-specific, and disease-
specific HRQOL questionnaires.

Generic questionnaires enable comparisons across various diseases and disciplines, while disease-specific ones detect more specific effects. The Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) is an example of a generic questionnaire, while the Dermatology Life Quality Index (DLQI) is a dermatology-specific tool. Both have demonstrated good validity and reliability.

On page 3 Dr. Alexa Kimball discusses the correlation between DLQI and PASI after analysing two double-blind, multicentre clinical trials of etanercept. She found good correlation between the two, but that the head and lower extremities had a greater weight on DLQI scores than areas covered by clothing (e.g. the trunk). In addition, one-third of the patients who did not achieve PASI 50 had 50 per cent or more improvement in the DLQI, affirming that meaningful improvement can be obtained without achieving a PASI 75, the bench mark required for drug approval.

Several investigators having been pushing for PASI 50 to be the benchmark. The Psoriasis Quality of Life-12 (PQOL-12) and Rosacea Quality of Life (RosaQoL) are two new disease-specific HRQOL questionnaires. The RosaQoL has three domains (symptoms, functioning and emotions) and 21 items. On page 3 Dr. Suephy Chen discusses its development. The PQOL-12 is a tool that was developed based on information from focus groups of patients with psoriasis. It is discussed by Dr. John Koo on page 4.