Table 2.
Characteristics of cases and controls
| Factor | Cases (n = 171) No. (%) | Controls (n = 342) No. (%) |
|---|---|---|
| Source of case | ||
| Laboratory database | 168 (98) | NA |
| ICD-9 diagnoses | 3 (2) | NA |
| Year of diagnosis or reference date | ||
| 1994–1999 | 119 (70) | 238 (70) |
| 2000–2004 | 52 (30) | 104 (30) |
| Age group (years) | ||
| 0–2 | 134 (78) | 270 (79) |
| 3–5 | 19 (11) | 36 (11) |
| 6–12 | 18 (11) | 36 (11) |
| Male sex | 83 (49) | 184 (54) |
| Race | ||
| White | 95 (56) | 148 (43) |
| African American | 11 (6) | 8 (2) |
| Asian | 9 (5) | 4 (1) |
| Hispanic | 9 (5) | 4 (1) |
| Other | 5 (3) | 3 (1) |
| Not in medical chart | 42 (25) | 175 (51) |
| Family medical records available | 147 (86) | 294 (86) |
| Any pneumococcal vaccination (1994–2004) | 11 (6) | 26 (8) |
| Polysaccharide (1994–2004) | 1 | 1 |
| Conjugate (2000–2004) | 10 | 25 |
| 4 doses | 6 | 12 |
| 1–3 doses | 4 | 13 |
ICD-9 = International Classification of Diseases, Ninth Revision; NA = not applicable.