The Minneapolis-Manchester Quality of Life Instrument: reliability and validity of the Adult Form in cancer survivors.

PURPOSE: Childhood cancer survivors are at risk for deficits in health-related quality of life (HRQL) as they age. Youth (8-12 years) and adolescent (13-20 years) versions of the Minneapolis-Manchester Quality of Life Instrument (MMQL) have been developed to address survivor-specific issues and are currently in use; the MMQL-Adult Form has now been developed to assess HRQL in childhood cancer survivors aged 21-55 years. METHODS: The MMQL-Adult Form was administered to 499 adults: 65 cancer patients on-therapy, 107 off-therapy, and 327 healthy controls. Forty-four percent of patients were under 30 years old at cancer diagnosis. Principal components analysis was performed. We evaluated internal consistency reliability, stability (re-administration of the MMQL-Adult Form 2 weeks later), construct validity (concurrent administration of the SF-36), and known-groups validity (score comparisons across the three groups). RESULTS: Principal components analysis resulted in retention of 44 items across six scales: social functioning, physical functioning, cognitive functioning, outlook on life, body image, and psychological functioning. Internal consistency (Cronbach's α) was 0.80-0.90 for individual scales and 0.95 overall. Strong intraclass correlations (0.98 overall) indicated high stability. The MMQL-Adult Form distinguished between known groups; healthy controls scored better than patients on four of six scales. The MMQL-Adult Form scales correlated highly with similar SF-36 scales, demonstrating construct validity. CONCLUSIONS: The MMQL-Adult Form is a reliable and valid self-report instrument for measuring multidimensional HRQL in cancer survivors. Development of this instrument ensures availability of a tool enabling cross-sectional and longitudinal assessment of HRQL in childhood cancer survivors as they age.