DOI: 10.1111/j.1741-6612.2007.00249.x 162 Australasian Journal on Ageing, Vol 26 No 4 December 2007, 162–167 © 2007 The Authors Journal compilation © 2007 ACOTA Blackwell Publishing Asia Research Measuring quality of life in older people: Reliability and validity of WHOQOL-OLD Nancye M Peel and Helen P Bartlett Australasian Centre on Ageing, The University of Queensland, Queensland, Australia Alison L Marshall* School of Human Movement Studies, The University of Queensland, Queensland, Australia Objectives: The World Health Organization (WHO) recently developed a generic Quality of Life (QOL) measure, the WHOQOL-OLD, specifically for use with older adults. This pilot study aimed to test the psychometric properties of the new measure to determine its suitability for evaluating outcomes of healthy ageing interventions. Methods: A random sample of 100 participants aged 65 years and older, selected from a database of community research volunteers, was invited to complete a mailed questionnaire administered at two time points. The questionnaire included the WHOQOL-OLD, a generic health-related QOL measure, the SF-12, as well as psychological and physical well-being measures and demographic data. Results and conclusion: Overall, the WHOQOL-OLD demonstrated good performance on tests of reliability and validity and had features that made it a more suitable outcome measure of QOL in older people compared with the frequently used measure, the SF-12. Key words: measurement scales, older age, quality of life, reliability, validity. Introduction As a response to global trends towards ageing of populations, policies aimed at enhancing the quality in the extended years of life have become part of health and social agendas in many countries [1]. Quality of Life (QOL) is therefore an important outcome measure for evaluating programs designed to promote healthy and active ageing [2]. The World Health Organization (WHO) defines QOL as ‘an individual’s perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns’ [3]. While there are many generic and disease-specific instruments to measure QOL [4], few have been developed and formally validated in populations of older people [5]. Generic instru- ments suitable for use in younger adult populations may fail to adequately address specific areas of QOL that may be more important and appropriate for older people [6]. Recently an add-on module for the WHO generic measures of QOL, the WHOQOL-OLD, was specifically developed for use with older adults [6]. This pilot study aimed to test the completion, reliability and validity of the WHOQOL-OLD, to determine its suitability for use in evaluating a physical activity intervention for sedentary older people. In the absence of a gold standard for measuring an abstract concept such as QOL [7], evidence of validity was assessed by comparison with the 12-item Short-Form Health Survey (SF-12). The SF-12 [8] has been used in Australian population surveys [9,10] and is considered a reliable measure of health-related QOL in older people [11]. Validity was also assessed by comparison with global judgements of health, measures of physical and mental well-being, and demographic variables. The measures of well-being included vitality (assessed using the Vitality Plus Scale [12]), anxiety and depression (Goldberg Symptom Inventory [13]) and psychological distress (Kessler 10 [14]). Methods Study design For this prospective study, a sample size of 29–47 was considered adequate to demonstrate a moderate to substantial correlation (r) of 0.4 – 0.5 [15] on test–retest measures, using an alpha of 0.05 and power of 80%. Based on an anticipated response rate of 70% and further loss to follow up of 20%, a sample of 100 was targeted for recruitment. The study was approved by the University of Queensland Behavioural and Social Sciences Ethical Review Committee. A random sample of participants (N = 100) was selected from the Australasian Centre on Ageing’s 50+ Registry (a pool of more than 600 research volunteers). Those eligible for the study were aged 65 years and over, English speaking and with no serious morbidity that would prevent participation. Those selected were invited to complete the mailed questionnaire at two time points (T1 and T2). The maximum time between questionnaire administrations was two weeks. Measures WHOQOL-OLD, a 24-item QOL measure, was developed by the WHOQOL Group as an add-on module to their QOL measures (WHOQOL-100 and WHOQOL-BREF), specifically for use Correspondence to: Dr Nancye M. Peel, Australasian Centre on Ageing, The University of Queensland. Email: n.peel@uq.edu.au *Present address: Health Promotion, School of Public Health, Queensland University of Technology, Victoria Park Road, Kelvin Grove, Qld 4059, Australia.