Characteristics of patients with rare diseases in primary care, National Ambulatory Medical Care Survey 2012–2014 (unweighted n=22 306, weighted n=354 507 772)
| Patients with rare diseases (%) | Patients without rare diseases (%) | P value | |
| Unweighted sample size | 363 | 21 943 | |
| Weighted sample size | 5 581 791 | 348 925 981 | |
| Mean age (years)* | 47.7 | 39.4 | <0.001 |
| Sex | |||
| Female | 56.4 | 53.8 | 0.44 |
| Race | |||
| Non-Hispanic White | 75.0 | 70.6 | 0.54 |
| Non-Hispanic Black | 8.6 | 10.1 | |
| Hispanics | 11.7 | 14.3 | |
| Others | 4.7 | 5.0 | |
| Insurance types | |||
| Private insurance | 49.3 | 54.6 | 0.15 |
| Public insurance | 47.3 | 40.0 | |
| Self-pay | 1.8 | 3.5 | |
| Other | 1.5 | 1.9 | |
| Major reasons for this visit* | |||
| New problems | 33.7 | 42.6 | 0.002 |
| Chronic problems | 39.0 | 28.7 | |
| Presurgery/postsurgery | 27.3 | 28.7 | |
| Preventive care | 0.0 | 0.0 | |
| Total number of chronic diseases* | 1.3 | 1.0 | 0.001 |
*Statistical significant level at 0.05.