Table 1. The relationship between the prevalence of C. difficile in lawn and the age of the lawn, its size, sampling site, location, postcode, and season in Perth.
| Variable | Variable categories | C. difficile number isolated (%) | Univariable model | Covariate Odds ratios (95% CI)* | |
|---|---|---|---|---|---|
| Odds ratios (95% CI)† | Sampling site | P value¶ | |||
| Age‡ | Old lawn (n = 113) | 53 (47) | Referent | ||
| New lawn (n = 198) | 129 (65) | 2.11 (1.32–3.4) | 2.30 (1.16–4.57) | 0.015# | |
| Area | Extra-large (n = 85) | 53 (62) | Referent | ||
| Large (n = 53) | 26 (49) | 0.58 (0.28–1.16) | 0.49 (0.16–1.49) | 0.7 | |
| Medium (n = 101) | 60 (59) | 0.88 (0.49–1.59) | 1.02 (0.42–2.51) | 0.7 | |
| Small (n = 72) | 43 (60) | 0.89 (0.47–1.71) | 0.88 (0.32–2.43) | 0.7 | |
| Location | North (n = 161) | 98 (60.9) | Referent | ||
| South (n = 150) | 84 (56) | 1.22 (0.78–1.92) | 1.25 (0.61–2.59) | 0.99 | |
| Season | Autumn (n = 224) | 135 (60.3) | Referent | ||
| Winter (n = 87) | 47 (54) | 0.77 (0.47–1.28) | 0.67 (0.28–1.62) | 0.52 | |
*CI; The 95% confidence interval of odds ratio for the covariate estimates.
†CI; The 95% confidence interval of odds ratio for the univariate estimates.
‡Age of lawn; new lawn ≤4 months, old lawn >4 months.
¶P values are based on likelihood ratios and P < 0.05 was considered significant#.
Univariable logistic regression model with random effect (site of sampling and postcode). The random effect term for postcode was not included in all the models because its addition or removal did not change the model estimates significantly.