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Table 4 Risk factors associated with Legionella isolation in univariate analysis

From: Legionella control in the water system of antiquated hospital buildings by shock and continuous hyperchlorination: 5 years experience

Risk factors Parameters Legionella isolation no. (%)  
   Yes No OR 95% CI p-value
Water temperature°C ≥20°C - ≤ 45°C 48 (13.3) 314 (86.7) 1.98 1.30 - 3.03 < 0.001
vs. <20°C or > 45°C 47 (7.2) 609 (92.8)
Residual free chlorine concentration mg/L < 0.5 90 (12.9) 610 (87.1) 5.3 2.63 - 10.65 < 0.001
vs. ≥ 0.5 9 (2.7) 323 (97.3)
Potability of water according to regulation Not potable water 9 (25.0) 27 (75.0) 4.48 1.87 - 10.74 0.001
vs. Potable water 21 (6.9) 282 (93.1)
No continuous vs. continuous hyperchlorination No continuous hyperchlorination 15 (27.3) 40 (72.7) 6.41 3.10 - 13.26 < 0.001
vs. Continuous hyperchlorination 23 (5.5) 393 (94.5)
Before vs. shock hyperchlorination at 15 days Before shock hyperchlorination 43 (21.1) 161 (78.9) 3.17 1.70 - 5.92 < 0.001
vs. Shock hyperchlorination at 15 days 15 (7.8) 178 (92.2)
Before vs. shock hyperchlorination at 30 days Before shock hyperchlorination 43 (21.1) 161 (78.9) 7.43 3.08 - 17.94 < 0.001
vs. Shock hyperchlorination at 30 days 6 (3.5) 167 (96.5)
Before vs. continuous hyperchlorination Before shock hyperchlorination 43 (21.1) 161 (78.9) 4.56 2.66 - 7.82 < 0.001
vs. Continuous hyperchlorination 23 (5.5) 393 (94.5)
Continuous vs. shock hyperchlorination at 30 days Continuous hyperchlorination 23 (5.5) 393 (94.5) 1.63 0.65 - 4.07 0.15
vs. Shock hyperchlorination at 30 days 6 (3.5) 167 (96.5)