Volume 23, Number 11—November 2017
Research
Weather-Dependent Risk for Legionnaires’ Disease, United States
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.