TABLE 1.
Descriptive statistics
| NHIS | Combined NAMCS and NHAMCS | |||
|---|---|---|---|---|
| Before Discontinuity (9 months) | After Discontinuity (9 months) a | Before Discontinuity (9 months) | After Discontinuity (9 months) a | |
| K6 (moderate‐to‐severe psychological distress) | 0.210 | 0.168 | — | — |
| Self‐reported LBP | 0.317 | 0.260 | — | — |
| Proportion of medical visits with LBP as primary reason | — | — | 0.011 | 0.009 |
| Proportion of postoperative medical visits | 0.024 | 0.025 | ||
| Health insurance | 0.847 | 0.837 | 0.863 | 0.867 |
| Age (25‐34) | 0.185 | 0.187 | 0.104 | 0.107 |
| Age (35‐44) | 0.219 | 0.213 | 0.140 | 0.132 |
| Age (45‐54) | 0.187 | 0.188 | 0.145 | 0.148 |
| Age (55‐64) | 0.118 | 0.122 | 0.114 | 0.118 |
| Age (65+) | 0.154 | 0.154 | 0.243 | 0.226 |
| Female | 0.518 | 0.519 | 0.574 | 0.588 |
| Black | 0.116 | 0.118 | 0.099 | 0.115 |
| Hispanic | 0.111 | 0.115 | 0.072 | 0.078 |
| Asian and Pacific Islander | 0.034 | 0.034 | 0.036 | 0.034 |
| Other Race | 0.036 | 0.035 | 0.006 | 0.006 |
| Region—west | 0.239 | 0.240 | 0.315 | 0.249 |
| Region—south | 0.454 | 0.459 | 0.395 | 0.458 |
| Family income $15‐20 000 | 0.064 | 0.061 | — | — |
| Family income $20‐25 000 | 0.071 | 0.073 | — | — |
| Family income $25‐35 000 | 0.132 | 0.130 | — | — |
| Family income $35‐45 000 | 0.110 | 0.110 | — | — |
| Family income $45‐55 000 | 0.098 | 0.092 | — | — |
| Family income $55‐65 000 | 0.077 | 0.077 | — | — |
| Family income $65 000+ | 0.239 | 0.247 | — | — |
| Employed (working at a job) | 0.283 | 0.284 | — | — |
| Associate's degree | 0.094 | 0.094 | — | — |
| Bachelor's degree | 0.156 | 0.161 | — | — |
| Postgraduate | 0.077 | 0.077 | — | — |
| Married (spouse in home) | 0.576 | 0.575 | — | — |
| Married (spouse not in home) | 0.012 | 0.012 | ||
| Divorced | 0.129 | 0.126 | — | — |
| Separated | 0.024 | 0.023 | — | — |
| Widowed | 0.063 | 0.062 | — | — |
| Health status—excellent | 0.309 | 0.305 | — | — |
| Health status—very good | 0.333 | 0.321 | — | — |
| Health status—good | 0.238 | 0.254 | — | — |
| Health status—fair | 0.088 | 0.090 | — | — |
| Observations | 20 349 | 20 254 | 52 993 | 59 213 |
a
Nine months beyond the discontinuity point for a total of 10 months. Note that the northeast of the United States is omitted to avoid including victims, first responders, and similar individuals in the sample as these may have physically injured their low back.