Table 2.
Absolute differences and agreement between self-reported and measured BMI in participants with and without OA
| Participants with clinical | Participants without clinical | P-value | |
|---|---|---|---|
| OA (n = 449) | OA (n = 151) | ||
| Normalweight (<25 kg/m2) | |||
| Difference between measured and self-reported BMI, mean (SD) | 0.64 (0.93) | -0.00 (1.49) | 0.000 |
| Poor agreement, n (%) | 3 (2.4) | 2 (4.3) | |
| Close agreement, n (%) | 42 (33.3) | 16 (34.0) | |
| Exact agreement, n (%) | 81 (64.3) | 29 (61.7) | 0.754 |
| Overweight (25–29.99 kg/m2) | |||
| Difference between measured and self-reported BMI, mean (SD) | 1.20 (1.60) | 1.05 (1.14) | 0.256 |
| Poor agreement, n (%) | 18 (10.8) | 3 (4.8) | |
| Close agreement, n (%) | 89 (53.6) | 35 (56.5) | |
| Exact agreement, n (%) | 59 (35.5) | 24 (38.7) | 0.406 |
| Obese (≥30 kg/m2) | |||
| Difference between measured and self-reported BMI, mean (SD) | 2.07 (1.95) | 1.26 (1.31) | 0.006 |
| Poor agreement, n (%) | 44 (28.0) | 3 (7.1) | |
| Close agreement, n (%) | 81 (51.6) | 27 (64.3) | |
| Exact agreement, n (%) | 32 (20.4) | 12 (28.6) | 0.010 |
Abbreviations: BMI Body Mass Index, kg kilograms, m meter, OA osteoarthritis. Poor agreement: ≥ ±2.00 kg/m2 difference, close agreement: ≥ ±1.00-1.99 kg/m2 difference, exact agreement: <±0-0.99 kg/m2 difference. Differences are the self-reported BMI (kg/m2) minus measured BMI (kg/m2). Positive values indicate underreporting, negative values indicate overreporting.