958
Davinder Singh et al
Fig. 2. Outbreak secondary attack rate versus time for influenza A H3N2 outbreaks. Table 2. Univariate and Final Model Predictor Odds Ratios for Influenza A H3N2 Infection
Model Predictions for Influenza Infection
Independent Variable
No. days from 2nd case of ILI to chemoprophylaxis (n=53)b No. days between 1st and 2nd cases (n=53)
No. days from declaring outbreak to chemoprophylaxis (n=53) Prevalence of ILI among residents (n=53)b,c No. residents at risk (n=53)d
Prevalence of ILI among staff (n=26)b,c Staff vaccinated (n=27), %c Residents vaccinated (n=40), %c Rural (yes or no) (n=53)e
Hand hygiene compliance (n=27)f Privately run (yes or no) (n=53)g
Unadjusted OR (95% CI) 1.33 (1.20–1.47) 0.99 (0.81–1.22) 1.31 (1.12–1.53) 1.07 (1.00–1.14) 0.44 (0.29–0.66) 1.26 (0.90–1.78) 0.98 (0.96–1.00) 1.00 (0.97–1.02) 1.83 (0.97–3.46) 1.00 (0.96–1.04) 0.57 (0.29–1.14)
Adjusted OR (95% CI)a
1.33 (1.21–1.46) 0.77 (0.66–0.90) … …
0.50 (0.36–0.70) … … … … … …
NOTE: n, number of facilities with available information; OR, odds ratio; ILI, influenza-like illness; LTCF, long-term care facility. Statistical test: hierarchical logistic regression. a(…) indicates that this variable was not included in the final model. bILI is characterized as acute onset of respiratory illness with fever and cough and with 1 or more of the following: sore throat, arthralgia, myalgia, or prostration that could be due to
influenza.9 cAt the start of the outbreak. dAt the start of the outbreak; OR represents change per 100 resident increase in an LTCF. eRural=a population less than 10,000 in the 2011 Health Canada census (1=Yes, 0=No). fHand hygiene score in the facility during the 2014–2015 influenza season. If >1 audit occurred during this time, scores were averaged. gFacilities not directly operated by the Regional Health Authority (1=yes, 0=no).
Table 3. Assessment of Independent Variable Collinearity Independent Variable
Days from 1st to 2nd case (n=53)
Days from 2nd case to oseltamivir (n=53) No. at risk at start of the outbreak (n=53) NOTE. Statistical test: linear regression.
Variance Inflation 1.41 1.34 1.17
concern about collinearity (Table 3). The main effects model was checked for any statistically significant interactions among the independent variables and the dependent variable. No statistically significant interactions were detected. Therefore, the final model for the influenza A H3N2analysiswas thesameasthe main-effectsmodel. The OR for the number of days from the second case to the start of oseltamivir in the final model was 1.33 (95% confidence
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140
