TABLE 3.
Incidence Rate Ratios† From Generalized Estimation Equations Models Estimated Using Data From Teenagers and Young Adults With Muscular Dystrophy in South Carolina 2000–2010
| ALL | ER | IP | PC | SP | TH | SUR | DR | CLTC | |
|---|---|---|---|---|---|---|---|---|---|
| Black race | 0.371*** (0.243–0.566) |
0.998 (0.661–1.508) |
1.623 (0.871–3.025) |
0.838 (0.532–1.319) |
0.697 (0.415–1.171) |
0.647 (0.107–3.898) |
1.299 (0.558–3.026) |
0.441* (0.178–1.091) |
0.0634*** (0.00985–0.407) |
| Other race and ethnicity | 1.377 (0.765–2.477) |
0.779 (0.451–1.343) |
0.602 (0.237–1.534) |
0.872 (0.492–1.545) |
1.352 (0.879–2.080) |
3.623 (0.518–25.34) |
0.723 (0.301–1.735) |
3.463*** (1.516–7.911) |
1.143 (0.483–2.704) |
| Young adult | 1.397*** (1.090–1.791) |
2.049*** (1.333–3.150) |
2.078 (0.852–5.072) |
0.99 (0.694–1.414) |
0.621 (0.318–1.215) |
0.174*** (0.0485–0.624) |
1.233 (0.564–2.695) |
0.344** (0.127–0.934) |
0.427 (0.0934–1.955) |
| Black young adult | 0.933 (0.632–1.378) |
2.011*** (1.381–2.930) |
3.043*** (1.648–5.618) |
1.145 (0.803–1.633) |
1.284 (0.866–1.906) |
1.048 (0.202–5.449) |
1.658* (0.917–2.997) |
0.793 (0.325–1.937) |
0.684 (0.356–1.314) |
| Other R/E young adult | 0.749 (0.470–1.194) |
0.665** (0.443–0.999) |
0.744 (0.404–1.369) |
0.771 (0.537–1.108) |
0.609*** (0.421–0.881) |
2.796 (0.490–15.94) |
0.716 (0.420–1.219) |
0.561 (0.191–1.652) |
0.88 (0.448–1.729) |
| Food stamps recipient‡ | 1.461*** (1.147–1.861) |
1.351** (1.045–1.746) |
1.464 (0.820–2.614) |
0.617** (0.414–0.918) |
0.786 (0.545–1.134) |
0.882 (0.186–4.192) |
1.055 (0.607–1.835) |
0.781 (0.390–1.565) |
1.718*** (1.232–2.397) |
| No high school completion§ | 0.823 (0.477–1.419) |
1.628* (0.939–2.824) |
1.236 (0.405–3.766) |
1.146 (0.664–1.978) |
2.581*** (1.396–4.773) |
0.222* (0.0394–1.255) |
1.648 (0.546–4.976) |
0.713 (0.0990–5.131) |
3.206 (0.514–20.00) |
| Lives in an Urban County | 0.728 (0.483–1.097) |
1.681* (0.994–2.842) |
3.094** (1.037–9.231) |
0.902 (0.274–2.966) |
0.906 (0.425–1.933) |
0.605 (0.126–2.915) |
5.967** (1.505–23.66) |
0.555 (0.152–2.022) |
0.661 (0.348–1.256) |
| # of observations | 1011 | 1011 | 1011 | 1011 | 1011 | 1011 | 1011 | 1011 | 1011 |
| # of individuals | 208 | 208 | 208 | 208 | 208 | 208 | 208 | 208 | 208 |
Significant at 10%.
Significant at 5%.
Significant at 1%. In parenthesis, 95% confidence intervals for the incidence rate ratio (IRRs) are reported.
All models are estimated using population averaged GEE model with equal correlation and robust standard errors assuming a negative binomial distribution. Coefficient estimates (βi) in a negative binomial regression are not directly interpretable; thus one needs to make the transformation eβi to get the incidence rate ratios (IRRs); the rate the outcome event happens as the control variable of interest changes by one unit, everything else constant. For example, looking at the first column (ALL) and comparing white teenagers to black teenagers incidence rate ratio is 0.371, which means black teenagers are 37% as likely to use care as white teenagers, that is, they are 63% less likely than their white counterparts. When comparing across multiple categories, say black young adults who received food stamps to white teenagers who did not receive food stamps incidence rate ratio (IRR) is 0.71 (0.371 × 1.397 × 0.933 × 1.461), that is the first group will be 29% less to use care compared with the latter group. GEE negative binomial population averaged model assumes as a default dispersion parameter is equal to 1. We estimated dispersion parameters for each model using cross section negative binomial estimation with clustered standard errors and used the estimated dispersion coefficient in XTGEE command to alter the default.
Food stamp receipt measure was calculated for each year a person was included in the cohort separately.
No recorded entry into 12th grade.
ALL indicates All Encounters; ER, Emergency Room Encounters; IP, Inpatient Care; PC, Primary Care; SP, Specialist Care; TH, Therapy; SUR, Surgery; DR, Developmental Rehabilitation; CLTC, community long-term care and Home Care.