Table 2.
Factors associated with recurrent flares among people classified as having CPPD disease with episodes of acute CPP crystal arthritis (N = 602)*
| Recurrent flares | Odds ratio (95% CI) | ||||
|---|---|---|---|---|---|
| No (n = 270) | Yes (n = 332) | Unadjusted | Model 1 a | Model 2 b | |
| Current age (y), mean (SD) | 74.4 (11.9) | 73.7 (12.0) | 0.99 (0.98–1.01) | 0.99 (0.98–1.01) | 0.99 (0.98–1.01) |
| Sex, n (%) | |||||
| Female (ref) | 153 (56.7) | 180 (54.2) | 1 | 1 | 1 |
| Male | 117 (43.3) | 152 (45.8) | 1.10 (0.80–1.52) | 1.09 (0.79–1.51) | 1.29 (0.90–1.84) |
| Symptom duration, n (%) | |||||
| ≤2 y (ref) | 141 (52.2) | 89 (26.8) | 1 | 1 | 1 |
| >2 y | 129 (47.8) | 243 (73.2) | 2.98 (2.12–4.20) | 3.05 (2.16–4.30) | 2.88 (2.00–4.14) |
| Acute arthritis | |||||
| Knee, n (%) | |||||
| No (ref) | 116 (43.0) | 71 (21.4) | 1 | 1 | 1 |
| Yes | 154 (57.0) | 261 (78.6) | 2.77 (1.94–3.95) | 2.77 (1.94–3.95) | 3.65 (2.41–5.51) |
| Wrist, n (%) | |||||
| No (ref) | 140 (51.8) | 147 (44.3) | 1 | 1 | 1 |
| Yes | 130 (48.1) | 185 (55.7) | 1.36 (0.98–1.87) | 1.38 (0.99–1.91) | 2.11 (1.38–3.22) |
| Persistent inflammatory arthritis, n (%) | |||||
| No (ref) | 199 (73.7) | 249 (75.0) | 1 | 1 | 1 |
| Yes | 71 (26.3) | 83 (25.0) | 0.93 (0.65–1.35) | 0.93 (0.64–1.35) | 0.71 (0.46–1.09) |
| CDS, n (%) | |||||
| No (ref) | 254 (94.1) | 307 (92.5) | 1 | 1 | 1 |
| Yes | 16 (5.9) | 25 (7.5) | 1.29 (0.68–2.47) | 1.27 (0.66–2.44) | 1.62 (0.76–3.43) |
| Metabolic or familial predisposition, n (%) | |||||
| No (ref) | 201 (74.4) | 239 (72.0) | 1 | 1 | 1 |
| Yes | 69 (25.6) | 93 (28.0) | 1.14 (0.79–1.63) | 1.14 (0.79–1.63) | 0.97 (0.65–1.46) |
| 2/3 MCPJ OA, n (%) | |||||
| No (ref) | 206 (76.3) | 236 (71.1) | 1 | 1 | 1 |
| Yes | 64 (23.7) | 96 (28.9) | 1.31 (0.91–1.89) | 1.34 (0.93–1.95) | 1.16 (0.73–1.85) |
| Any STTJ OA, n (%) | |||||
| No (ref) | 210 (77.8) | 238 (71.7) | 1 | 1 | 1 |
| Yes | 60 (22.2) | 94 (28.3) | 1.38 (0.95–2.01) | 1.43 (0.98–2.01) | 1.11 (0.69–1.77) |
| Any wrist OA, n (%) | |||||
| No (ref) | 202 (74.8) | 216 (65.1) | 1 | 1 | 1 |
| Yes | 68 (25.2) | 116 (34.9) | 1.59 (1.12–2.28) | 1.66 (1.16–2.39) | 1.42 (0.90–2.24) |
| Any SLAC wrist, n (%) | |||||
| No (ref) | 249 (92.2) | 308 (92.8) | 1 | 1 | 1 |
| Yes | 21 (7.8) | 24 (7.2) | 0.92 (0.50–1.70) | 0.94 (0.51–1.72) | 0.77 (0.38–1.53) |
| Number of joints with CC, median (IQR) | 2 (1–4) | 2 (1–4) | 1.01 (0.90–1.13) | 1.02 (0.91–1.14) | 0.91 (0.80–1.04) |
Statistically significant associations are shown in bold typeface. CC, chondrocalcinosis; CDS, crowned dens syndrome; CI, confidence interval; CPP, calcium pyrophosphate; CPPD, calcium pyrophosphate deposition; IQR, interquartile range; MCPJ, meta‐carpo‐phalangeal joint; OA, osteoarthritis; ref, reference; SLAC, scapho‐lunate advanced collapse; STTJ, scapho‐trapezo‐trapezoid joint.
Adjustment for age and sex.
Adjustment for all covariates: current age (years), gender, symptom duration (>2 or ≤ 2 years), acute knee arthritis (yes/no), acute wrist arthritis (yes/no), only one or recurrent acute episodes, persistent inflammatory arthritis (yes/no), CDS (yes/no), metabolic or familial predisposition (yes/no), MCPJ OA (yes/no), STTJ OA (yes/no), wrist OA (yes/no), SLAC wrist (yes/no), and number of joints with CC.