Table 5.
MODEL A: multivariate logistic regression of risk factors affecting LF antigen and antibody positivity: sociodemographic, residence and knowledge covariates, all participants (n = 638–641)
| Factor | Level | Ag (n = 641) | Bm14 Ab (n = 641) | Wb123 Ab (n = 638) | Any Ab (n = 638) | ||||
|---|---|---|---|---|---|---|---|---|---|
| OR (95% CI) | P | OR (95% CI) | P | OR (95% CI) | P | OR (95% CI) | P | ||
| Sampling site | Clinic vs Cannery | 2.52 (0.65–9.75)* | 0.182 | 0.52 (0.24–1.13)** | 0.099 | ||||
| Age group (years) | 15–24 | Ref | Ref | Ref | |||||
| 25–34 | 1.21 (0.32–4.61) | 0.779 | 0.64 (0.21–1.94) | 0.431 | 0.55 (0.21–1.42) | 0.219 | |||
| 35–44 | 3.75 (1.21–11.63)*** | 0.022 | 1.36 (0.54–3.40) | 0.511 | 1.46 (0.67–3.19) | 0.342 | |||
| 45–54 | 3.76 (1.22–11.67)*** | 0.022 | 1.70 (0.69–4.21) | 0.252 | 1.38 (0.62–3.05) | 0.427 | |||
| > 55 | 4.17 (1.12–15.51)*** | 0.033 | 0.63 (0.15–2.70) | 0.536 | 1.35 (0.49–3.72) | 0.557 | |||
| Gender | Male vs female | 2.64 (0.78–8.94)* | 0.118 | 3.44 (2.04–5.82)**** | < 0.001 | 3.63 (2.11–6.27)**** | < 0.001 | 3.49 (2.21–5.49)**** | < 0.001 |
| SES quantile | Per decr. quantile | 2.89 (1.09–7.69)*** | 0.033 | 1.30 (0.92–1.84)* | 0.136 | 1.46 (1.02–2.11)*** | 0.041 | 1.51 (1.12–2.05)**** | 0.007 |
| Years lived in AS | < 9 | Ref | Ref | Ref | |||||
| 9–14 | 2.26 (0.89–5.72)** | 0.086 | 1.62 (0.67–3.90) | 0.283 | 2.00 (0.91–4.40)** | 0.083 | |||
| > 14 | 1.22 (0.55–2.70) | 0.624 | 0.76 (0.37–1.57) | 0.462 | 1.12 (0.58–2.13) | 0.741 | |||
| Ever been outside AS | Yes vs no | 1.80 (0.75–4.32)* | 0.190 | ||||||
| Know swelling or genitourinary symptom | Yes vs no | 0.29 (0.06–1.41)* | 0.125 | ||||||
| Know acute symptoms | Yes vs no | 3.53 (0.98–12.74)** | 0.054 | 1.60 (0.86–2.95)* | 0.135 | ||||
| Know mosquito as cause | Yes vs no | 0.65 (0.38–1.09)* | 0.102 | 0.55 (0.32–0.95)*** | 0.032 | 0.56 (0.36–0.90)*** | 0.016 | ||
| Constant | 0.0009 (0.0003–0.03)**** | < 0.001 | 0.02 (0.003–0.09)**** | < 0.001 | 0.07 (0.02–0.32)**** | < 0.001 | 0.03 (0.01–0.13)**** | < 0.001 | |
| Log-likelihood | − 52.969305 | − 206.46537 | − 197.11102 | − 259.59574 | |||||
| Log-likelihood (inc. county) | − 48.999694 | − 200.41316 | − 190.39068 | − 253.82438 | |||||
| LR Chi-square | 21.25** | 0.068 | 57.07**** | < 0.001 | 60.62**** | < 0.001 | 72.60**** | < 0.001 | |
| Pseudo R2 | 0.1782 | 0.1246 | 0.1373 | 0.1251 | |||||
*P < 0.2, **P < 0.1, ***P < 0.05, ****P < 0.01
Abbreviations: Ag: antigen (ICT and/or Og4C3); AS, American Samoa; n, no. positive; N, no. tested; na, not available (zero cases); Ref, reference category; inc., including; LR, likelihood ratio