Osteoporosis Assessment Questionnaire-Physical Function (OPAQ-PF): a psychometrically validated osteoporosis-targeted patient reported outcome measure of daily activities of physical function

Abstract

SummaryThe purpose of this study was to evaluate the measurement properties of the Osteoporosis Assessment Questionnaire-Physical Functioning (OPAQ-PF). Based on this study, the OPAQ-PF has confirmed unidimensionality and acceptable reliability, construct validity, and sensitivity to change in a recent fracture/no recent fracture osteoporosis sample.MethodsDimensionality was established through exploratory and confirmatory factor analysis. Patients completed three patient reported outcome (PRO) measures and four performance-based measures (PBMs) at baseline to enable an evaluation of construct validity. Patients without a recent fracture completed the OPAQ-PF 2 weeks after baseline to enable an evaluation of test–retest reliability. Ability to detect change and interpretation of change were investigated following completion of the OPAQ-PF 12 and 24 weeks postbaseline by patients with a recent fracture.ResultsA prospective psychometric validation study in 144 postmenopausal women, with moderate to severe osteoporosis, 37 of whom had experienced a recent fragility fracture (<6 weeks). Unidimensionality was established for the OPAQ-PF by factor analysis. The OPAQ-PF had good internal consistency (α = 0.974) and test–retest reliability (mean intraclass correlation coefficient (ICC) 0.993. The OPAQ-PF differentiated between patients with/without recent fracture, and by severity of osteoarthritis; it correlated strongly with hypothesized-related scales and PBMs (r > 0.3, p < 0.001). Ability to detect change was established with high correlations between changes in OPAQ-PF score and changes in global concept scores in recent fracture patients (r ≥ 0.6, 24-week change). Effect size of change on OPAQ-PF score increased by level of global change (p < 0.001). Anchor-based methods identified an OPAQ-PF change of 10 at an individual patient level and 20 at a group level as meaningful to patients.ConclusionsThe OPAQ-PF has confirmed unidimensionality and acceptable reliability, construct validity, and sensitivity to change in a recent fracture/no recent fracture osteoporosis sample.

Interpreting change from patient reported outcome (PRO) endpoints: patient global ratings of concept versus patient global ratings of change, a case study among osteoporosis patients

“…The overall sample ( n = 144), comprised 107 patients without recent fracture and 37 recent fracture patients. Baseline sample characteristics are presented in Table 1 (further details reported elsewhere [ 10 ]).…”

“…The OPAQ-PF [ 9 , 10 ] is designed to evaluate the participant’s ability to perform their daily activities of physical function during the past seven days. The instrument covers mobility (5 items), physical positions (6 items) and transfers (4 items).…”

“…A qualitative study with 32 participants demonstrated content validity of the OPAQ-PF in post-menopausal women who had, and had not, previously sustained a fracture [ 9 ]. A prospective study of 144 postmenopausal women with moderate to severe osteoporosis demonstrated that the OPAQ-PF was: unidimensional; had good internal consistency (α = 0.974); good test-retest reliability (ICC = 0.993); differentiated between patients with/without a recent fracture and by severity of osteoporosis; and correlated strongly with hypothesized-related scales and performance based measures (r ≥ 0.6, p < 0.001) [ 10 ].…”

“…Full study procedures are reported elsewhere [ 10 ]. Participants completed the OPAQ-PF and the three ratings of concept at baseline.…”

“…Improvement was expected among recent fracture participants during this time period. Participants with a recent fracture also attended a visit at 24 weeks post-baseline [ 10 ]; these data are not used in the current analysis because the rating of change items asked the patients to compare their functioning with the previous visit (week 12) rather than baseline.…”