Table 3.
Associations from univariable logistic regression models, adjusting for matching of cases and controls, between catastrophic musculoskeletal injury and exercise history variables for Thoroughbred racehorses in California, 2012–2013.
| Cases (n = 42) | Controls (n = 95) | Odds ratio (95% CI) | p-value | |||
|---|---|---|---|---|---|---|
| n | Median (IQR) | n | Median (IQR) | |||
| Horse age (d) | 42 | 1410 (1133, 1770) | 95 | 1375 (1119, 1729) | 1.00 (1.00, 1.00) | 0.398 |
| Horse sex | ||||||
| Male gelding | 14 | – | 37 | – | Reference | |
| Male entire | 13 | – | 22 | – | 1.56 (0.69, 3.53) | 0.285 |
| Female | 15 | – | 36 | – | 1.10 (0.55, 2.20) | 0.785 |
| Career | ||||||
| Raced | ||||||
| Previously raced | 35 | – | 79 | – | Reference | |
| Unraced | 7 | – | 16 | – | 0.99 (0.42, 2.32) | 0.977 |
| Races (No.) | 42 | 11 (4, 17) | 95 | 6 (2, 13) | 1.41 (1.09, 1.83)a | 0.010 |
| Works (No.) | 42 | 27 (16, 43) | 95 | 24 (13, 43) | 1.08 (0.84, 1.39)a | 0.555 |
| Events (No.) | 42 | 39.5 (23, 63) | 95 | 29 (15, 56) | 1.13 (0.89, 1.45)a | 0.313 |
| Race distance (f) | 42 | 63.25 (26.5, 111.5) | 95 | 39.5 (9, 84.5) | 1.31 (1.03, 1.68) | 0.029 |
| Work distance (f) | 42 | 111.5 (69, 172) | 95 | 101 (51, 188) | 1.05 (0.84, 1.32) | 0.640 |
| Total (event) distance (f) | 42 | 174.75 (105.5, 318.5) | 95 | 139 (65, 267) | 1.09 (0.89, 1.35) | 0.407 |
| Mean race distance (f) | 35 | 6.13 (5.43, 6.70) | 79 | 6.50 (5.75, 7.45) | 0.73 (0.51, 1.04) | 0.077 |
| Mean work distance (f) | 41 | 4.14 (3.80, 4.33) | 95 | 4.18 (3.71, 4.47) | 0.89 (0.52, 1.50) | 0.652 |
| Mean event distance (f) | 41 | 4.67 (4.29, 4.88) | 95 | 4.67 (4.00, 5.03) | 0.92 (0.65, 1.31) | 0.657 |
| Career length (d) | 42 | 532 (212, 876) | 95 | 487 (192, 808) | 1.14 (0.93, 1.40) | 0.218 |
| Active career length (d) | 42 | 425 (170, 678) | 95 | 117 (301, 531) | 1.15 (0.92, 1.44)a | 0.212 |
| Layup | ||||||
| Number of layups | 42 | 1 (0, 2) | 95 | 1 (0, 2) | 1.06 (0.72, 1.56) | 0.756 |
| Total layup time (d) | 42 | 144 (0, 317) | 95 | 130 (0, 277) | 1.00 (1.00, 1.00) | 0.801 |
| Mean layup time (d) | 42 | 125.5 (0, 187.5) | 95 | 114 (0, 185) | 1.00 (1.00, 1.00) | 0.745 |
| Percentage of career in layup | 42 | 26.51 (0, 37.54) | 95 | 23.27 (0, 40.41) | 1.00 (0.98, 1.01) | 0.811 |
| Time since last layup (d) | 42 | 194.5 (116, 372) | 95 | 136 (75, 232) | 1.22 (0.96, 1.54)a | 0.102 |
| Events since last layup (No.) | 42 | 22 (14, 37) | 95 | 15 (10, 26) | 1.01 (0.99, 1.02) | 0.236 |
| Rate | ||||||
| Career | ||||||
| Races per year | 42 | 6.15 (4.23, 9.82) | 95 | 4.93 (2.25, 8.51) | 2.03 (1.25, 3.31)a | 0.004 |
| Works per year | 42 | 17.96 (13.11, 33.57) | 95 | 23.69 (7.46, 32.68) | 0.76 (0.51, 1.12)a | 0.161 |
| Events per year | 42 | 26.06 (19.71, 41.48) | 95 | 29.58 (23.79, 40.56) | 0.79 (0.50, 1.25)a | 0.314 |
| Distance raced (f/mo) | 42 | 3.12 (2.25, 5.09) | 95 | 2.39 (1.19, 4.33) | 1.10 (0.96, 1.27) | 0.167 |
| Distance worked (f/mo) | 42 | 6.37 (4.40, 10.90) | 95 | 8.40 (6.12, 11.56) | 0.93 (0.85, 1.01) | 0.081 |
| Distance events (f/mo) | 42 | 10.45 (7.50, 15.08) | 95 | 11.75 (8.67, 15.56) | 0.96 (0.90, 1.02) | 0.194 |
| Time between races (d) | 34 | 38.86 (57.33, 78.47) | 72 | 69.77 (42.96, 111.49) | 0.99 (0.98, 1.00) | 0.011 |
| Time between works (d) | 40 | 20.75 (11.58, 29.10) | 93 | 15.83 (11.73, 21.27) | 1.03 (1.00, 1.06) | 0.025 |
| Time between events (d) | 40 | 14.29 (9.09, 19.05) | 94 | 12.58 (9.73, 15.42) | 1.02 (0.99, 1.06) | 0.245 |
| Active | ||||||
| Races per year | 42 | 9.39 (5.93, 11.23) | 95 | 7.47 (3.82, 10.43) | 1.97 (1.09, 3.58)a | 0.025 |
| Works per year | 42 | 29.87 (21.53, 39.60) | 95 | 34.88 (27.71, 43.34) | 0.62 (0.37, 1.05)a | 0.078 |
| Events per year | 42 | 37.65 (32.53, 47.20) | 95 | 42.69 (36.73, 48.88) | 0.48 (0.19, 1.22)a | 0.122 |
| Distance raced (f/mo) | 42 | 4.57 (3.19, 5.77) | 95 | 3.70 (2.09, 5.81) | 1.04 (0.93, 1.15) | 0.503 |
| Distance worked (f/mo) | 42 | 9.98 (7.37, 12.18) | 95 | 12.01 (8.99, 14.81) | 0.89 (0.82, 0.97) | 0.010 |
| Distance events (f/mo) | 42 | 14.71 (11.97, 16.85) | 95 | 16.24 (13.46, 18.86) | 0.90 (0.83, 0.97) | 0.006 |
| Time between races (d) | 34 | 40.99 (32.62, 49.63) | 72 | 46.66 (34.84, 76.90) | 0.99 (0.97, 1.00) | 0.061 |
| Time between works (d) | 40 | 12.60 (10.30, 16.87) | 93 | 10.93 (9.00, 13.79) | 1.06 (0.99, 1.14) | 0.078 |
| Time between events (d) | 40 | 10.16 (8.18, 11.45) | 94 | 8.90 (7.90, 10.48) | 1.16 (1.01, 1.32) | 0.035 |
| Exercise intensity (slope) | ||||||
| Slope at start | 34 | 12.69 (8.78, 16.62) | 86 | 12.79 (9.73, 15.83) | 0.99 (0.91, 1.08) | 0.839 |
| Slope at date of death | 39 | 12.71 (8.35, 16.42) | 92 | 16.62 (13.37, 20.66) | 0.87 (0.82, 0.92) | <0.001 |
| Slope after last layup | 24 | 14.95 (8.93, 16.90) | 60 | 16.84 (13.13, 19.24) | 0.89 (0.81, 0.98) | 0.014 |
| Recent cumulative distances | ||||||
| 1 month (f) | 42 | 14 (7.5, 19.5) | 95 | 19 (14, 24) | 0.91 (0.87, 0.95) | <0.001 |
| 2 months (f) | 42 | 26 (15, 34) | 95 | 33.5 (19.5, 40.5) | 0.96 (0.94, 0.99) | 0.008 |
| 4 months (f) | 42 | 57.25 (27.5, 71.5) | 95 | 53 (30, 72) | 1.00 (0.99, 1.01) | 0.781 |
| 6 months (f) | 42 | 70.50 (31.5, 103) | 95 | 65 (42, 102) | 1.00 (0.99, 1.01) | 0.666 |
| 8 months (f) | 42 | 92.75 (45.5, 119) | 95 | 75.5 (43, 114) | 1.00 (1.00, 1.01) | 0.570 |
| 10 months (f) | 42 | 108.5 (48.5, 144) | 95 | 86 (48, 125) | 1.00 (1.00, 1.01) | 0.668 |
| 12 months (f) | 42 | 109.25 (48.5, 159.5) | 95 | 88.5 (52, 149) | 1.00 (1.00, 1.01) | 0.796 |
| Month 2 (f) | 42 | 12.75 (4.5, 16.5) | 95 | 13.5 (6.5, 18) | 0.99 (0.94, 1.03) | 0.557 |
| Months 3 and 4 (f) | 42 | 31 (12.5, 39) | 95 | 20 (7, 35) | 1.02 (1.00, 1.04) | 0.044 |
| Months 5 and 6 (f) | 42 | 24 (1, 31.5) | 95 | 10 (0, 32) | 1.01 (1.00, 1.03) | 0.145 |
| Month 1 minus month 2 (f) | 42 | 0.00 (-3, 7.5) | 95 | 5.5 (2, 11) | 0.91 (0.85, 0.97) | 0.004 |
Median values presented are untransformed and based on the pooled unmatched data. d, day; mo, month; No., number; f, furlong.
a
Odds ratios determined from transformed data using the log base 2.