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Evaluation of clinically relevant states in patient reported outcomes in knee and hip osteoarthritis: the patient acceptable symptom state

F Tubach¹, P Ravaud¹, G Baron¹, B Falissard², I Logeart³, N Bellamy⁴, C Bombardier⁵, D Felson⁶, M Hochberg⁷, D van der Heijde⁸, M Dougados⁹

¹ Institut National de la Santé et de la Recherche Médicale (INSERM) E 0357; Département d’Epidémiologie, Biostatistique et Recherche Clinique; Groupe Hospitalier Bichat-Claude Bernard (Assistance Publique—Hôpitaux de Paris); Faculté Xavier Bichat (Université Paris 7), Paris, France
² Faculté de Médecine Paris-sud, Département de Santé Publique, Hôpital Paul Brousse (Assistance Publique—Hôpitaux de Paris), Villejuif, France
³ Merck, Sharp & Dohme Chibret Laboratories, Paris, France
⁴ Department of Medicine, University of Queensland, Royal Brisbane Hospital, Brisbane, Queensland, Australia
⁵ Institute for Work and Health, Toronto, Ontario, Canada
⁶ Boston University School of Medicine, Boston, Massachusetts, USA
⁷ University of Maryland, Baltimore, Maryland, USA
⁸ University Hospital, Maastricht, The Netherlands
⁹ Service de Rhumatologie B, Hôpital Cochin (Assistance Publique—Hôpitaux de Paris), Paris, France

Correspondence to:
Dr F Tubach
Département d’Epidémiologie, Biostatistique et Recherche Clinique, INSERM E0357, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France; florence.tubach{at}bch.ap-hop-paris.fr

Background: The patient acceptable symptom state (PASS) is the value beyond which patients can consider themselves well. This concept can help in interpreting results of clinical trials.

Objective: To determine the PASS estimate for patients with knee and hip osteoarthritis (OA) by assessing pain, patient’s global assessment of disease activity, and functional impairment.

Methods: A 4 week prospective multicentre cohort study of 1362 outpatients with knee or hip OA was carried out. Data on assessment of pain and patient’s global assessment of disease, measured on visual analogue scales, and functional impairment, measured on the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) function subscale, were collected at baseline and final visits. The patients assessed their satisfaction with their current state at the final visit. An anchoring method based on the patient’s opinion was used.

Results: For patients with knee and hip OA, the estimates of PASS were, respectively, 32.3 and 35.0 mm for pain, 32.0 and 34.6 mm for patient global assessment of disease activity, and 31.0 and 34.4 points for WOMAC function score. The PASS varied moderately across the tertiles of baseline scores but not across age, disease duration, or sex.

Conclusion: The use of PASS in clinical trials would provide more meaningful results expressed as a proportion of patients in an acceptable symptom state.

Abbreviations: LDA, low disease activity; MCID, minimal clinically important difference; MCII, minimal clinically important improvement; NSAID, non-steroidal anti-inflammatory drug; OA, osteoarthritis; PASS, patient acceptable symptom state; VAS, visual analogue scale; WOMAC, Western Ontario McMaster Universities Osteoarthritis Index

Keywords: functional impairment; hips; osteoarthritis; knees; outcome criteria; treatment

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