Table 1.
Socio-demographic characteristics by case status, N (column %) or Mean (SD)
| Variable | Value | Controls | Keratoconus Cases | Total | p-value |
|---|---|---|---|---|---|
| Total, N (row %) | 16,053 (50.0) | 16,053 (50.0) | 32,106 | ||
| Age at Enrollment * | 40.4 (13.0) | 40.4 (13.0) | 40.4 (13.0) | 0.98 | |
| Time in Plan (years) | 4.6 (2.9) | 4.7 (2.9) | 4.7 (2.9) | 0.0002 | |
| Number of Eye Visits | 2.6 (3.2) | 6.5 (7.1) | 4.6 (5.8) | < 0.0001 | |
| Sex * | Male | 9,456 (58.9) | 9,456 (58.9) | 18,912 (58.9) | 1.00 |
| Female | 6,597 (41.1) | 6,597 (41.1) | 13,194 (41.1) | ||
| Race (Nmiss=3,391) | White | 11,367 (79.0) | 10,708 (74.8) | 22,075 (76.9) | < 0.0001 |
| Black | 1,055 (7.3) | 1,467 (10.2) | 2,522 (8.8) | ||
| Latino | 1,209 (8.4) | 1,535 (10.7) | 2,744 (9.6) | ||
| Asian | 612 (4.3) | 414 (2.9) | 1,026 (3.6) | ||
| Other | 152 (1.1) | 196 (1.4) | 348 (1.2) | ||
| Education (Nmiss=2,076) | Less than High School | 178 (1.2) | 206 (1.4) | 384 (1.3) | < 0.0001 |
| High School Diploma | 4,089 (27.2) | 3,331 (22.2) | 7,420 (24.7) | ||
| Some College | 6,446 (42.9) | 6,507 (43.4) | 12,953 (43.1) | ||
| College Diploma | 4,236 (28.2) | 4,866 (32.4) | 9,102 (30.3) | ||
| Advanced Degree | 71 (0.5) | 100 (0.7) | 171 (0.6) | ||
| Income (Nmiss=5,327) | < $30K | 550 (4.1) | 540 (4.0) | 1,090 (4.1) | < 0.0001 |
| $30K – < $60K | 4,560 (34.0) | 4,054 (30.3) | 8,614 (32.2) | ||
| $60K – < $100K | 3,591 (26.8) | 3,577 (26.8) | 7,168 (26.8) | ||
| $100K – < $125K | 1,829 (13.6) | 1,939 (14.5) | 3,768 (14.1) | ||
| ≥ $125K | 2,879 (21.5) | 3,260 (24.4) | 6,139 (22.9) | ||
| Urban/Rural Status (Nmiss=240) | Urban | 14,213 (89.1) | 14,660 (92.1) | 28,873 (90.6) | < 0.0001 |
| Large Rural | 915 (5.7) | 684 (4.3) | 1,599 (5.0) | ||
| Small Rural | 815 (5.1) | 579 (3.6) | 1,394 (4.4) | ||
| Diabetes | None | 13,450 (83.8) | 13,991 (87.2) | 27,441 (85.5) | < 0.0001 |
| Uncomplicated | 1,731 (10.8) | 1,517 (9.4) | 3,248 (10.1) | ||
| Complicated | 872 (5.4) | 545 (3.4) | 1,417 (4.4) | ||
| Asthma | 1,721 (10.7) | 2,292 (14.3) | 4,013 (12.5) | < 0.0001 | |
| Allergic Rhinitis | 4,115 (25.6) | 4,549 (28.3) | 8,664 (27.0) | < 0.0001 | |
| Mitral Valve Prolapse | 873 (5.4) | 853 (5.3) | 1,726 (5.4) | 0.62 | |
| Collagen Vascular Disease | 209 (1.3) | 170 (1.1) | 379 (1.2) | 0.04 | |
| Aortic Aneurysm | 96 (0.6) | 90 (0.6) | 186 (0.6) | 0.66 | |
| Down Syndrome | 8 (0.0) | 62 (0.4) | 70 (0.2) | < 0.0001 | |
| Sleep Apnea | 1,402 (8.7) | 1,697 (10.6) | 3,099 (9.7) | < 0.0001 | |
| Depression | 1,200 (7.5) | 1,210 (7.5) | 2,410 (7.5) | 0.83 | |
| Clinical Risk Group * | 1 (Healthiest) | 5,178 (32.3) | 5,178 (32.3) | 10,356 (32.3) | 1.00 |
| 2 | 4,486 (27.9) | 4,486 (27.9) | 8,972 (27.9) | ||
| 3 | 6,186 (38.5) | 6,186 (38.5) | 12,372 (38.5) | ||
| 4 (Least healthy) | 203 (1.3) | 203 (1.3) | 406 (1.3) |
*
Matching variable
Continuous variables compared using two-sample t-tests, and categorical variables compared using Chi-square tests.
Uncomplicated Diabetes defined as lack of end-organ damage.
Complicated Diabetes defined as having accompanying end-organ damage.