Table 3.
Final model for conditional logistic regression on anemia matched for day of presentation on Pemba Island, Zanzibar, Tanzania*
| Predictor | Univariate regressions (n = 120 cases and 556 controls) 95% CI | Multivariate model 1 (n = 114 cases and 527 controls) | Multivariate model 2 (n = 49 cases and 243 controls) | |||||
|---|---|---|---|---|---|---|---|---|
| No. cases (%) | No, controls (%) | Univariate OR (P) | 95% CI | Multivariate OR (P) | 95% CI | Multivariate OR (P) | 95% CI | |
| Age, months | ||||||||
| 1–6 | 15 (12.5) | 80 (14.3) | Reference | Reference | Reference | |||
| 7–12 | 68 (56.6) | 217 (39) | 2.36 (0.003) | 1.28–4.38 | 1.82 (0.060) | 0.98–3.41 | 0.36 (0.284) | 0.54–2.35 |
| ≥ 13 | 37 (30.8) | 259 (45.5) | 0.94 (0.846) | 0.49–1.18 | 0.88 (0.699) | 0.46–1.68 | 0.11 (0.011) | 0.21–0.61 |
| Sex | ||||||||
| M | 65 (54.1) | 274 (49.2) | Reference | Reference | Reference | |||
| F | 55 (45.8) | 282 (50.8) | 0.69 (0.037) | 0.49–0.98 | 0.82 (0.351) | 0.55–1.24 | 0.58 (0.381) | 0.17–1.97 |
| Household income ($/month) | ||||||||
| < 10 | 48 (40) | 201 (36.1) | Reference | Reference | Reference | |||
| ≥ 10 | 72 (60) | 355 (63.9) | 0.55 (0.003) | 0.37–0.82 | 0.53 (0.006) | 0.38–0.84 | 0.61 (0.469) | 0.15–2.31 |
| Malaria at previous visit† | ||||||||
| No | 74 (64.9) | 404 (76.6) | Reference | Reference | ||||
| Yes | 40 (35.1) | 123 (23.4) | 1.89 (0.003) | 1.23–2.87 | 1.78 (0.014) | 1.12–2.81 | ||
| Parasite density at previous visit (log10/μL) | 2.1 (SD 1.7) | 1.6 (SD 1.7) | 1.22 (< 0.001) | 1.09–1.37 | 1.75 (0.031) | 1.05–2.91 | ||
| Parasite density at current visit (log10/μL) | 2.1 (SD 1.9) | 1.5 (SD 1.8) | 1.29 (< 0.001) | 1.15–1.45 | 0.95 (0.731) | 0.70–1.29 | ||
| Pneumonia at visit prior to current visit | ||||||||
| No | 107 (93.8) | 511 (96.4) | Reference | Reference | ||||
| Yes | 7 (6.2) | 19 (3.6) | 14.07 (0.001) | 2.90–68.15 | 11.63 (0.005) | 2.07–65.21 | ||
| Gametocytes at current visit | ||||||||
| No | 114 (95) | 550 (98.9) | Reference | Reference | Reference | |||
| Yes | 6 (5) | 6 (1.1) | 6.13 (0.001) | 2.04–18.43 | 6.24 (0.005) | 1.72–22.58 | 11.07 (0.030) | 1.27–96.54 |
| Information on MOI only available in a limited data set | ||||||||
| MOI at current visit‡ | ||||||||
| 1 | 30 (38.9) | 128 (42.1) | Reference | Reference | ||||
| 2 | 26 (33.7) | 76 (25) | 2.66 (0.005) | 1.35–5.25 | 7.05 (0.036) | 1.14–43.57 | ||
| 3 | 17 (22.0) | 46 (15.1) | 2.00 (0.114) | 0.85–4.68 | 2.00 (0.328) | 0.50–7.90 | ||
| ≥ 4 | 4 (5.1) | 54 (17.7) | 0.82 (0.627) | 0.38–1.79 | 0.06 (0.012) | 0.01–0.55 | ||
| MOI at prior visit§ | ||||||||
| 1 | 29 (39.1) | 175 (40.5) | Reference | Reference | ||||
| 2 | 22 (29.7) | 116 (26.8) | 1.39 (0.279) | 0.77–2.52 | 3.04 (0.134) | 0.71–13.02 | ||
| 3 | 14 (18.9) | 62 (14.3) | 1.84 (0.115) | 0.86–3.93 | 3.58 (0.256) | 0.40–32.32 | ||
| ≥ 4 | 9 (12.1`) | 79 (18.2) | 0.60 (0.250) | 0.24–1.44 | 0.24 (0.129) | 0.04–1.51 | ||
OR = odds ratio; CI = confidence interval; MOI = multiplicity of infection.
As per definition 3: ≥ 10 parasites/μL plus history of fever or documented fever. Information on previous malaria was not available for the time window –5 to –21 days in 10 cases and 84 controls.
Information on MOI at current visit (–5 to –21 days) was not available in 43 cases and 252 controls. These are microscopy-negative cases and microscopy-positive cases in which the polymerase chain reaction did not yield a result.
Information on MOI at previous visit (–5 to –21 days) was not available in 46 cases and 124 controls. These are microscopy-negative cases and microscopy-positive cases in which the polymerase chain reaction did not yield a result.