Table 1.
Characteristics of the Study Groups.*
| Characteristic | Case Patients (N = 381) |
Community Control Patients (N = 380) |
Hospital Control Patients (N = 377) |
| Area — no. (%)† | |||
| Urban | 205 (53.8) | 203 (53.4) | 201 (53.3) |
| Rural | 176 (46.2) | 177 (46.6) | 176 (46.7) |
| Sex — no. (%) | |||
| Female | 203 (53.3) | 191 (50.3) | 180 (47.7) |
| Male | 178 (46.7) | 189 (49.7) | 197 (52.3) |
| Age — mo‡ | 20.4±12.8 | 25.3±13.1 | 22.5±12.1 |
| Jaundice — no./total no. (%)§ | 19/379 (5.0) | 1/380 (0.3) | 0/376 |
| Splenomegaly — no./total no. (%)§¶ | 237/372 (63.7) | 108/363 (29.8) | 86/349 (24.6) |
| Fever — no./total no. (%)‖** | 189/376 (50.3) | 41/375 (10.9) | 172/374 (46.0) |
| Hemoglobin — g/dl§†† | 3.6±0.8 | 9.9±1.9 | 9.6±2.2 |
| Mean corpuscular volume — fl§‡‡ | 82.9±15.2 | 75.5±9.3 | 74.2±9.7 |
| Reticulocyte count — ×10−9/liter‡§§ | |||
| Median | 53.2 | 76.8 | 64.5 |
| Interquartile range | 30.2–91.7 | 46.4–114.7 | 43.0–103.2 |
| Admitted to hospital — no. (%)† | 381 (100) | 3 (0.8) | 17 (4.5) |
| Died in hospital — no. (%)† | 24 (6.3) | 0 | 0 |
Plus-minus values are means ±SD.
No statistical tests were applied.
P<0.05 for differences among all three groups (by Tukey post hoc test or Kruskal.Wallis test with Tukey multiple comparisons).
Community and hospital control patients were significantly different from case patients (P<0.05 by Tukey post hoc test). Case patients had a primary diagnosis of severe anemia (defined as a hemoglobin concentration of <5.0 g per deciliter).
Splenomegaly was defined as more than 1 cm of palpable spleen below the left costal margin in the midaxillary line.
Community control patients were significantly different from case patients and hospital control patients (P<0.05 by Tukey post hoc test).
Fever was defined as an axillary temperature of more than 37.5°C.
Hemoglobin values were recorded in 373 community control patients and 375 hospital control patients.
Mean corpuscular volume was recorded in 316 case patients 322 community control patients and 314 hospital control patients.
Reticulocyte values were recorded in 266 case patients, 284 community control patients, and 279 hospital control patients.