Original Article
OAKHQOL: A new instrument to measure quality of life in knee and hip osteoarthritis

https://doi.org/10.1016/j.jclinepi.2004.04.011Get rights and content

Abstract

Objective

To develop a questionnaire with which to measure quality of life (QoL) in patients with knee and hip osteoarthritis (OA).

Study design and setting

Thirty-two caregivers and 96 OA patients were interviewed individually (using cognitive and face-to-face techniques) and in focus groups. A group of experts working independently at first and then consensually used the interview transcripts to generate a 46-item questionnaire.

Results

Analysis of questionnaires completed by 263 patients with hip or knee OA resulted in the exclusion of three items (two because of low reliability and one because of a low response rate). Principal component analysis revealed four factors: physical activity, mental health, social functioning, and social support. A pain dimension was individualized. Preliminary testing showed the reliability of the five dimensions to be satisfactory (intraclass correlation coefficients: 0.70–0.85), construct validity was adequate when correlated with the SF36 (Spearman correlation coefficients: 0.43–0.75), and discrimination was satisfactory. The osteoarthritis knee and hip quality of life questionnaire (OAKHQOL) consists of 43 items in five dimensions and three independent items.

Conclusion

The OAKHQOL is the first specific knee and hip OA quality of life instrument. Its development followed an a priori structured strategy to ensure content validity. It meets psychometric requirements for validity and reliability.

Introduction

Osteoarthritis (OA) is a chronic disease and a major cause of pain and disability. An estimated 7–11% of the populations of developed countries have symptomatic OA, and 27–44% have radiographic disease; the annual incidence in the United Kingdom is reported to be 3.1% [1], [2], [3]. As OA increases in prevalence with age, the growing proportion of elderly people in the populations of many countries will lead to it becoming an increasingly important global public health problem. OA already accounts for considerable expenditure by health care providers [4], [5], and the cost to OA patients themselves can be substantial [6]. Apart from its economic consequences, OA is a major cause of disability, quality of life impairment, and social dysfunction [6]. It should therefore be a high priority for health care professionals, researchers, and public health decision-makers.

There is a growing interest in using quality of life (QoL) assessment to help investigate the impact of new pharmaceutical products and other interventions. The US FDA guide for clinical development programs in OA recommends that efficacy endpoints include: a measure of pain, patient global assessment, and a self-administered questionnaire covering pain and function (McMaster Western Ontario questionnaire [WOMAC] or Lequesne's index) [7], [8]. QoL instruments are particularly valuable in patient global assessment because of their ability to capture more than just pain and disability [9].

Several tools have been used to measure health-related quality of life (HRQoL) among patients with OA of the lower limbs [7], [10] and those undergoing total hip or knee surgery [11], [12], [13], [14], [15], [16]. The Medical Outcomes Study Short-Form 36 (SF36) has been widely applied but, as a generic instrument, tends to be less responsive than specific instruments [17], particularly in the context of a medical or rehabilitation intervention rather than joint replacement. Comparisons of the SF36 with a disease-specific instrument (WOMAC) in patients undergoing knee replacement surgery report that they measure different aspects of health and should probably be used together [12], [13]. However, no specific HRQoL instrument has been developed for patients with OA of the lower limb. WOMAC [7] and Lequesne's index [8] measure pain and functional disability but do not take other domains of QoL into account. The Arthritis Impact Measurement Scales (AIMS2) tool [18] and its short form AIMS2-SF [19] have been considered for use in OA but have a limited usefulness among patients with a high prevalence of lower limb disability [20].

There is a clear need for a disease-specific instrument with good content, construct validity, and responsiveness in assessing the QoL of patients with lower limb OA. We hypothesized that specific aspects of QoL are encountered by patients with knee and hip OA. Apart from affecting physical activities, knee or hip OA may also have an impact on mental health in terms of anxiety and depression, on sleep, on sexuality, and on social functioning [21], [22]. Some specific aspects like social support have also already been demonstrated to be of importance in this pathology [23]. The combination of the SF36 with the WOMAC or the Lequesne index may thus not capture these specific aspects of HRQoL expressed by patients with knee and hip OA. The knee and hip osteoarthritis quality of life questionnaire (OAKHQOL) should be more able to apprehend aspects specifically appropriate to knee and hip OA patients.

Our aim was to develop a new instrument (OAKHQOL) with the ability to capture a patient's perception of his or her disease and with the psychometric properties required for use in clinical trials and observational studies. As the construction process of a QoL instrument has a major influence on its content and construct validity, OAKHQOL was developed a priori. The present article reports its conception, development, and early testing.

Section snippets

Materials and methods

OAKHQOL was developed in three stages: first, a qualitative stage to define the concept and content of the instrument, elicit verbatim remarks, build categories, and generate items; second, a quantitative stage to examine the properties of items, and determine the dimensional and factorial structure of the finished questionnaire; and third, preliminary psychometric analysis (item-scale correlations, construct validity, reliability).

Qualitative stage

One hundred twenty-eight patients and 32 health professionals participated in this stage. The initial analysis of interview transcripts identified 119 relevant items, of which, 83 were pertinent and related to QoL. The first version of the OAKHQOL 1.0 was a self-administered questionnaire of 46 items reported in terms of their frequency and intensity.

Sample characteristics

Of 263 patients recruited in outpatient clinics, 139 were being treated medically, 97 were scheduled for surgery, and 27 had undergone total

Discussion

The OAKHQOL is the first specific knee and hip OA quality of life instrument. Its development followed an a priori structured strategy to ensure content validity. It meets psychometric requirements for validity and reliability.

The intention when developing OAKHQOL was to introduce elements of QoL that patients with hip and knee OA at various stages of severity report as affecting their daily lives. Within the framework provided by WHO, the a priori strategy adopted has allowed for the

Acknowledgments

The authors wish to thank M. Alfonsi, F. Arnould, X. Ayral, P. Bouillot, I. Cahitte, I. Chary-Valckenaere, P. Chaspoux, C. Cuny, J.P. Delagoutte, P. Fener, H. Gaudin, M.F. Gérard, F. Goupy Le Maitre, J. P. Gros, D. Hannouche, E. Hiraux, N. Jeanson, J.M. Lardry, D. Loeuille, D. Mainard, D. Nebout, G. Osnowycz, H. Ouakil, S. Perrot, S. Poiraudeau, J. Pourel, P. Prost, P. Rabany, M. Rousseau, Dr. Thomas, F Touzard, G. Vançon, L. Vastel, and J.P. Voilquin. This study was conducted with the support

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