AIDSQuest: The HIV/AIDS Survey Library
Survey Summaries

Medical Outcomes Study (MOS): Derived Quality-of-life Measures

NOTE: The following summary is excerpted from a review of quality of life instruments. To view the full review, please see Appendix F: Review of Instruments Assessing Health-related Quality of Life in the survey library.

General overview
Questionnaires developed from the Medical Outcomes Study are the most widely used health status instruments in HIV research (Wu et al. 1997b). These measures include the MOS-HIV, SF-12, SF-20, SF-21, SF-36, SF-38, SF-56, and the HIV Cost and Service Utilization Study (HCSUS). There is also a version called the IQOLA being developed for international use. These questionnaires cover between 2 and 11 dimensions and utilize between 12 and 56 questions (as per their names). The MOS instruments generally take a short time to complete (< 15 minutes) with subscales scored from 0 to 100. Most of these instruments provide overall scores and often include the separation of physical and mental health scores. In addition, there is extensive credibility for the construct and predictive validity, reliability, and responsiveness of these instruments as these instruments have been administered to over 20,000 patients (Wu et al. 1997a). The most commonly used instruments for HIV research are the MOS-SF-36, MOS-SF-20, and the MOS-HIV. 

Overview: MOS-SF-36 (36-item questionnaire)
This multidimensional tool is the most widely used health status instrument worldwide. This instrument uses a 36-item questionnaire on eight dimensions: physical functioning, bodily pain, role limitations due to physical health problems, role limitations due to personal or emotional problems, general mental health, social functioning, energy/fatigue, and general health perceptions. In addition to this, it provides a single item for perceived change in health. Items are scored and aggregated to provide a scale ranging from 0 to 100 (0 = poor health and 100 = good health).

Methodology/validity: MOS-SF-36
The SF-36 can be either self-administered or administered by a trained interviewer and takes about 5–10 minutes to complete. This questionnaire has high internal consistency and strong psychometric properties (Vanhems et al. 1996). The SF-36 has demonstrated high reliability (Hays & Shapiro 1992) and it has good responsiveness to change in clinical conditions (Bowling 1997). The results can be machine scored and the scale has been evaluated in large population studies (Kaplan 1998). The subscales are not aggregated to give the global score, making them more complicated to score. Mean scores are obtained on each subscale, which has a tendency to distort the results due to outlying values. The questionnaire has not been developed through extensive consultation with the general population. This questionnaire does not contain age-specific questions and may not be appropriate at each age level (Kaplan 1998). The bodily pain scale has been reported to show low convergent validity with severity of illness and independent pain scores. Furthermore, floor and ceiling effects have been reported for the SF-36 (Bowling 1997).

Overview: MOS-SF-20 (20-item questionnaire; short form)
This instrument utilizes a brief 20-item questionnaire for assessing HRQOL in both a cross-sectional and a longitudinal design (Hays and Shapiro 1992). The SF-20 consists of six dimensions: physical functioning, mental health, role functioning, social functioning, health perceptions, and pain.

Methodology/validity: MOS-SF-20
Data for the SF-20 have shown high reliability and construct validity. The SF-20 has shown floor effects with hospitalized patients and contains no sexual dimension.

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This page updated 21 August 2006

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