Table 1. Characteristics of study sample.
| Lyme disease sample * , † | Matched controls ‡ | |
|---|---|---|
| No. (%) | No. (%) | |
| Total | 52,795 (100) | 263,975 (100) |
| Sex | ||
| Female | 27,138 (51.4) | 135,690 (51.4) |
| Male | 25,657 (48.6) | 128,285 (48.6) |
| Age | ||
| 0–4 years | 1,176 (2.2) | 5,880 (2.2) |
| 5–9 years | 2,722 (5.2) | 13,610 (5.2) |
| 10–20 years | 6,713 (12.7) | 33,565 (12.7) |
| 21–44 years | 16,182 (30.7) | 80,910 (30.7) |
| 45–64 years | 26,002 (49.3) | 130,010 (49.3) |
| Region | ||
| Northeast | 19,921 (37.7) | 99,605 (37.7) |
| Mid-Atlantic | 12,553 (23.8) | 62,765 (23.8) |
| Great Lakes | 9,587 (18.2) | 47,935 (18.2) |
| Appalachian | 4,145 (7.9) | 20,735 (7.9) |
| Southeast | 3,927 (7.4) | 19,635 (7.4) |
| Central | 1,534 (2.9) | 7,670 (2.9) |
| Pacific | 561 (1.1) | 2,805 (1.1) |
| Plains & Mountains | 321 (0.6) | 1,605 (0.6) |
| Desert | 246 (0.5) | 1,230 (0.5) |
* Lyme disease sample includes only those persons with a test order and antibiotic treatment within 30 days of the test order, a diagnosis and antibiotic treatment within 30 days of the diagnosis, or a diagnosis, test order and antibiotic treatment within 30 days. The Lyme disease sample includes only those with 18 consecutive months of enrollment, including a 6-month “clean period” of enrollment prior to Lyme disease episode in which they were neither diagnosed with nor tested for Lyme disease.
† Lyme disease and control samples are restricted to persons under 65 years of age, with commercial health insurance plans.
‡ Controls were matched to Lyme disease cases on age, sex, region, payer and enrollment year. Control group includes only those with 12 consecutive months of enrollment in a commercial health insurance plan. Control group was restricted to persons with outpatient costs greater than $0.