Table 2.
Results extracted from the studies included in the meta-analysis
| Author and year of publication | Temperature variable and range (°C) | RR/rate ratio (95% CI) | Temperature threshold | Units of study results | Outcome and subgroup |
|---|---|---|---|---|---|
| Hansen et al., 2008 [12] | Mean temperature (4.4 to 41.9) | Hospital admissions for renal disease during heat waves (3 or more consecutive days when daily maximum temperatures reached or exceeded 35°C in the warm season) compared with non-heat wave periods | Hospital admissions for renal disease (Adelaide) | ||
| 1.10 (1.00, 1.22) | 35 | All | |||
| 1.12 (0.98, 1.26) | 35 | Male | |||
| 1.10 (1.03, 1.15) | 35 | Female | |||
| 1.13 (1.02, 1.26) | 35 | 15-64 y | |||
| 1.16 (0.99, 1.33) | 35 | Male | |||
| 1.10 (1.02, 1.18) | 35 | Female | |||
| 1.09 (0.98, 1.20) | 35 | ≥ 65 y | |||
| 1.05 (0.92, 1.20) | 35 | Male | |||
| 1.08 (0.99, 1.19) | 35 | Female | |||
| 1.20 (1.04, 1.38) | 35 | ≥ 85 y | |||
| 1.05 (0.82, 1.34) | 35 | Male | |||
| 1.22 (1.02, 1.45) | 35 | Female | |||
| Pincus et al., 2010 [26] | Mean temperature (14.2 to 30.1) | 1.29 (1.15, 1.43) | - | The summer/winter ratio of renal colic incidence | Presentations of renal colic, all, Melbourne |
| Tawatsupa et al., 2012 [27] | Heat stress | Incidence of kidney disease during heat stress compared with non-heat stress | Incidence of kidney disease, Bangkok | ||
| 1.48 (1.01, 2.16) | - | Male | |||
| 0.87 (0.59, 1.28) | - | Female | |||
| Lin et al., 2013 [10] | Mean temperature (14.2 to 30.1) | 1.45 (1.27, 1.64) | 30 | Kidney disease hospital admissions at 30°C compared with at 25°C | Kidney disease hospital admissions, all, 7 study areas in Taiwan |
| Bobb et al., 2014 [28] | Heat wave | 1.14 (1.06, 1.23) | - | Hospitalization for renal failure during heat wave periods compared with non-heat wave periods | Hospitalization for renal failure, all, USA |
| Tasian et al., 2014 [22] | Mean temperature (-22 to 36) | The cumulative RR for a daily mean temperature of 30°C vs. 10°C | Kidney stone presentation, all | ||
| 1.38 (1.07, 1.79) | 30 | Atlanta | |||
| 1.37 (1.07, 1.76) | 30 | Chicago | |||
| 1.36 (1.10, 1.69) | 30 | Dallas | |||
| 1.11 (0.73, 1.68) | 30 | Los Angeles | |||
| 1.47 (1.00, 2.17) | 30 | Philadelphia | |||
| Ordon et al., 2016 [23] | Mean temperature (-7.0 to 25.4) | The effect of increased ambient temperatures on daily emergency department visits for renal colic (extreme heat effect: 99th vs. 10th percentile) | Daily emergency department visits for renal colic (Ontario) | ||
| 1.48 (1.33, 1.64) | 25.4 | All | |||
| Age (y) | |||||
| 1.32 (1.08, 1.60) | 25.4 | 19-39 | |||
| 1.52 (1.24, 1.86) | 25.4 | 40-49 | |||
| 1.83 (1.48, 2.27) | 25.4 | 50-59 | |||
| 1.44 (1.06, 1.96) | 25.4 | 60-69 | |||
| 1.14 (0.80, 1.63) | 25.4 | ≥70 | |||
| Sex | |||||
| 1.64 (1.43, 1.88) | 25.4 | Male | |||
| 1.22 (1.04, 1.44) | 25.4 | Female | |||
| Yang et al., 2016 [24] | Mean temperature (4.8 to 33.9), minimum temperature (1.8 to 29.7), maximum temperature (7.0 to 40.0) | 1.92 (1.21, 3.05) | 30.7 | RR comparing the 90th percentile of temperature distribution with the reference (21.0°C) | Daily emergency ambulance dispatches for renal colic, all, Guangzhou |
| Moyce et al., 2017 [29] | Heat strain | 1.34 (1.04, 1.74) | - | Incidence of acute kidney injury during heat strain compared with non-heat strain | Acute kidney injury cumulative incidence, all, California |
| Ogbomo et al., 2017 [30] | Extreme heat | Hospitalization for renal diseases during extreme-heat periods (daily mean temperature above the 97th percentile on lag day 0) compared with non-extreme-heat periods | Hospitalization for renal diseases | ||
| 1.14 (1.02, 1.27) | - | All (Michigan) | |||
| 1.14 (1.07, 1.22) | - | Wayne | |||
| 1.16 (0.91, 1.46) | - | Washtenaw | |||
| 0.86 (0.57, 1.31) | - | Ingham | |||
| Lim et al., 2017 [25] | Mean temperature | Percentage change in the risk of acute kidney injury admissions stratified by baseline temperatures <28.8°C and ≥28.8°C | Acute kidney injury admissions, Seoul | ||
| 2.04 (1.58, 2.64) | 28.8 | All | |||
| Sex | |||||
| 2.33 (1.69, 3.23) | 28.8 | Male | |||
| 1.66 (1.09, 2.52) | 28.8 | Female | |||
| Age (y) | |||||
| 2.04 (1.47, 2.83) | 28.8 | <75 | |||
| 2.04 (1.35, 3.08) | 28.8 | ≥75 |
RR, relative risks; CI, confidence interval.