Volume 23, Number 11—November 2017
Research
Weather-Dependent Risk for Legionnaires’ Disease, United States
Jacob E. Simmering, Linnea A. Polgreen, Douglas B. Hornick, Daniel K. Sewell, and Philip M. Polgreen
Table 4
Effects of humidity and temperature on Legionnaires’ disease risk, United States, 1998–2011*
| Variable | Odds ratio | 95% CI |
|---|---|---|
| Age, y | ||
| 18–30 | 1.00 | Ref |
| 31–40 | 2.60 | 2.30–2.95 |
| 41–50 | 2.23 | 2.87–3.62 |
| 51–60 | 3.22 | 2.88–3.61 |
| 61–70 | 2.29 | 2.04–2.57 |
| 71–80 | 1.74 | 1.54–1.96 |
| 81–90 | 1.37 | 1.21–1.55 |
| >91 |
0.78 |
0.66–0.93 |
| Race/ethnicity | ||
| White | 1.00 | Ref |
| Black | 1.37 | 1.31–1.44 |
| Hispanic | 1.05 | 0.96–1.13 |
| Other |
1.00 |
0.93–1.10 |
| Payer | ||
| Medicare | 1.00 | Ref |
| Medicaid | 0.87 | 0.81–0.93 |
| Private | 2.43 | 2.32–2.53 |
| Uninsured | 1.86 | 1.71–2.03 |
| Other |
1.65 |
1.48–1.83 |
| Sex | ||
| M | 1.00 | Ref |
| F |
0.75 |
0.73–0.78 |
| Hospital admission mo | ||
| Jan | 1.00 | Ref |
| Feb | 0.85 | 0.77–0.94 |
| Mar | 0.74 | 0.67–0.82 |
| Apr | 0.91 | 0.82–1.00 |
| May | 1.10 | 0.99–1.23 1.35–1.71 |
| Jun | 1.52 | |
| Jul | 2.24 | 1.99–2.52 |
| Aug | 2.49 | 2.21–2.80 |
| Sep | 2.35 | 2.10–2.64 |
| Oct | 2.58 | 2.37–2.80 |
| Nov | 1.63 | 1.49–1.79 |
| Dec |
1.14 |
1.04–1.25 |
| Year |
1.06 |
1.06–1.07 |
| Hospital latitude, °N | ||
| Latitude | 3.06 | 2.67–3.50 |
| Latitude squared |
0.99 |
0.99–0.99 |
| Total monthly rainfall† | ||
| Dry | 1.00 | Ref |
| Normal | 1.36 | 1.29–1.44 |
| Wet |
1.47 |
1.38–1.57 |
| Mean monthly temperature, °F | ||
| <60 | 1.00 | Ref |
| 60–80 | 0.55 | 0.44–0.68 |
| >80 |
1.57 |
1.24–1.98 |
| Mean RH, % | ||
| 0–50.0 | 1.00 | Ref |
| 50.1–55.0 | 0.85 | 0.68–1.06 |
| 55.1–60.0 | 0.58 | 0.48–0.70 |
| 60.1–65.0 | 0.66 | 0.56–0.78 |
| 65.1–70.0 | 0.79 | 0.67–0.93 |
| 70.1–75.0 | 0.80 | 0.68–0.94 |
| 75.1–80.0 | 0.76 | 0.64–0.90 |
| 80.1–100.0 |
0.65 |
0.53–0.78 |
| Interactions | ||
| Temperature 60°–80°F | ||
| RH <50% | 1.0 | Ref |
| RH 50.1%–55.0% | 1.65 | 1.19–2.28 |
| RH 55.1%–60.0% | 1.54 | 1.13–2.09 |
| RH 60.1%–65.0% | 2.15 | 1.68–2.75 |
| RH 65.1%–70.0% | 2.27 | 1.83–2.83 |
| RH 70.1%–75.0% | 2.93 | 2.36–3.64 |
| RH 75.1%–80.0% | 3.27 | 2.62–4.08 |
| RH 80.1%–100.0% | 4.79 | 3.71–6.17 |
| Temperatures >80°F | ||
| RH <50% | 1.0 | Ref |
| RH 50.1%–55.0% | 0.00 | – |
| RH 55.1%–60.0% | 0.00 | – |
| RH 60.1%–65.0% | 1.23 | 0.77–1.95 |
| RH 65.1%–70.0% | 0.62 | 0.42–0.91 |
| RH 70.1%–75.0% | 0.38 | 0.24–0.60 |
| RH 75.1%–80.0% | 0.91 | 0.54–1.54 |
| RH 80.1%–100.0% | 0.00 | – |
*Based on a multivariable logit model with a diagnosis of Legionnaires’ disease as the outcome variable. The analysis comprised data from 26 states: Arizona, Arkansas, California, Colorado, Connecticut, Illinois, Iowa, Kentucky, Maryland, Massachusetts, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Jersey, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Utah, Vermont, Virginia, Washington, Wisconsin. Dash indicates 95% CIs not defined because there were no data for cases or controls in that particular strata.
†Dry, <18 mm; normal, 18–85.85 mm; wet, >85.85 mm.
Page created: October 16, 2017
Page updated: October 16, 2017
Page reviewed: October 16, 2017
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