Temperature Ranges and Positivity Rates and Adjusted Rate Ratios for Associations of Daily Ambient Temperatures with Fecal Immunochemical Test Positivity Rate, Kaiser Permanente–Northern California (KPNC) 2007 to 2013
| Temperature Categories | Average of the Minimum–Maximum, °C, mean (range) | Positive % | Positivity Rate Ratio (95% Confidence Interval) |
|---|---|---|---|
| Temperature levels | |||
| 1 (lowest) | 9.6 (8.0 to 11.1) | 5.5 | 1.00 |
| 2 | 11.7 (10.3 to 12.9) | 4.4 | 0.82 (0.78 to 0.86) |
| 3 | 14.3 (12.7 to 15.8) | 4.4 | 0.82 (0.77 to 0.86) |
| 4 | 17.5 (15.5 to 19.4) | 4.2 | 0.78 (0.75 to 0.82) |
| 5 (highest) | 18.7 (16.7 to 20.7) | 4.3 | 0.81 (0.76 to 0.86) |
| Seasons | |||
| Winter | 10.9 (9.5 to 12.4) | 4.5 | 1.00 |
| Spring | 14.8 (12.6 to 16.5) | 4.1 | 0.92 (0.90 to 0.96) |
| Summer | 18.3 (16.1 to 20.1) | 4.2 | 0.93 (0.90 to 0.96) |
| Autumn | 15.4 (13.1 to 17.9) | 5.1 | 1.13 (1.09 to 1.17) |
| Test result month (individually) | |||
| January | 10.0 (8.5 to 11.7) | 4.8 | 0.83 (0.77 to 0.90) |
| February | 11.0 (9.8 to 12.4) | 4.3 | 0.74 (0.69 to 0.79) |
| March | 11.8 (10.4 to 13.0) | 4.3 | 0.75 (0.70 to 0.80) |
| April | 13.5 (11.8 to 14.9) | 4.2 | 0.73 (0.68 to 0.77) |
| May | 15.2 (13.5 to 16.5) | 4.1 | 0.72 (0.67 to 0.77) |
| June | 17.3 (15.3 to 19.0) | 4.1 | 0.72 (0.67 to 0.77) |
| July | 18.1 (16.1 to 19.8) | 3.9 | 0.69 (0.64 to 0.74) |
| August | 18.5 (16.2 to 20.5) | 4.2 | 0.74 (0.69 to 0.79) |
| September | 18.9 (16.7 to 20.9) | 4.4 | 0.77 (0.71 to 0.82) |
| October | 17.2 (15.4 to 18.6) | 4.9 | 0.85 (0.79 to 0.91) |
| November | 13.7 (11.8 to 15.5) | 5.2 | 0.91 (0.84 to 0.98) |
| December | 9.9 (8.4 to 11.5) | 5.8 | 1.00 |
| Test result month (grouped in pairs) | |||
| December/January | 10.0 (8.4 to 11.7) | 5.2 | 1.00 |
| February/March | 11.4 (10.2 to 12.7) | 4.3 | 0.84 (0.80 to 0.88) |
| April/November | 13.6 (11.8 to 15.1) | 4.5 | 0.87 (0.83 to 0.91) |
| May/October | 15.9 (14.1 to 17.4) | 4.4 | 0.86 (0.82 to 0.90) |
| June/July | 17.7 (15.7 to 19.4) | 4.0 | 0.79 (0.76 to 0.83) |
| August/September | 18.6 (16.4 to 20.6) | 4.3 | 0.84 (0.80 to 0.88) |
Ambient temperature levels were defined using the mean and 1.25 times the standard deviation (SD) of maximum temperatures by year aggregated over weekly intervals, >mean + 1.25 SD, >mean, >means-1.25 SD, and <means + 1.25 SD (reference), in that order. Thus, the highest and lowest temperature levels were 1.25 times the level above or below the mean, respectively.
Each set of estimates (by level, month, and by season of the year) was generated individually using generalized estimating equations with logit link and exchangeable covariance matrix, adjusted for age, sex, and medical region. The estimates are relative ratios from the predictive margins.