Table 2

Parameter estimates, 95% confidence intervals, standard errors for intercept, race and comorbidity in linear mixed model (LMM*) of HbA1c using sampling and random effects Meta-regression, in for Veterans with Type 2 Diabetes (2002-2006)
Simple random sample (SRS)
Parameter Sample (%) Intercept Non-hispanic black Hispanic Other 1 Comorbidity 2 Comorbidities 3+ Comorbidities
β (95% CI) 100 7.54 (7.52, 7.55) 0.46 (0.45, 0.46) 0.29 (0.28, 0.30) 0.25 (0.23, 0.25) 0.01 (0.01, 0.02) 0.04 (0.04, 0.05) 0.11 (0.11, 0.13)
25 7.59 (7.55, 7.61) 0.46 (0.44, 0.47) 0.31 (0.28, 0.32) 0.24 (0.22, 0.25) 0.01 (0.00, 0.02) 0.02 (0.01, 0.04) 0.10 (0.08, 0.13)
10 7.54 (7.48, 7.58) 0.47 (0.44, 0.48) 0.30 (0.26, 0.32) 0.26 (0.23, 0.27) 0.03 (0.02, 0.05) 0.08 (0.07, 0.12) 0.08 (0.05, 0.13)
5 7.54 (7.48, 7.62) 0.44 (0.41, 0.47) 0.28 (0.23, 0.32) 0.27 (0.24, 0.30) 0.03 (0.01, 0.06) 0.05 (0.02, 0.09) 0.13 (0.08, 0.18)
SE 100 0.0115 0.005 0.007 0.005 0.0037 0.0054 0.0079
25 0.0115 0.005 0.007 0.005 0.0037 0.0054 0.0080
10 0.0115 0.005 0.007 0.005 0.0037 0.0054 0.0080
5 0.0116 0.005 0.0069 0.005 0.0037 0.0053 0.0079
Stratified random sampling (StRS)
Parameter Sample (%) Intercept Non-Hispanic Black Hispanic Other 1 Comorbidity 2 Comorbidities 3+ Comorbidities
β (95% CI) 25 7.61 (7.57, 7.63) 0.47 (0.45, 0.48) 0.28 (0.26, 0.29) 0.26 (0.24, 0.27) 0.01 (0, 0.02) 0.03 (0.02, 0.05) 0.11 (0.11, 0.15)
10 7.58 (7.53, 7.63) 0.46 (0.43, 0.48) 0.28 (0.25, 0.30) 0.26 (0.23, 0.28) 0.0 (-0.01, 0.02) 0.05 (0.03, 0.08) 0.16 (0.13, 0.2)
5 7.61 (7.54, 7.68) 0.38 (0.35, 0.41) 0.30 (0.26, 0.35) 0.25 (0.21, 0.28) 0.02 (0.0, 0.05) 0.05 (0.02, 0.09) 0.09 (0.05, 0.15)
SE 25 0.0111 0.0049 0.0068 0.005 0.0037 0.0054 0.0079
10 0.0111 0.0049 0.0068 0.0049 0.0037 0.0054 0.0078
5 0.0111 0.0050 0.0069 0.005 0.0037 0.0053 0.0079
Random effects meta-regression without VISN 13 & 14 (REMR)
Parameter** Sample (%) Intercept Non-Hispanic Black Hispanic Other 1 Comorbidity 2 Comorbidities 3+ Comorbidities
β(95% CI) 100 7.58 (7.54, 7.62) 0.45 (0.41, 0.49) 0.08, (0.04, 0.12) 0.23 (0.19, 0.27) 0.01 (-0.04, 0.05) 0.03 (-0.01, 0.07) 0.09 (0.05, 0.13)

*-Independent variables used in fitting the linear mixed model were: linear time; race (non-Hispanic white reference, indicator variables); sex (female reference); marital status (single reference), service disability percentage, residence status (urban/rural, rural reference), VISN region (Northeast, Mid-Atlantic, South, Midwest, and West), and number of comorbidities (1, 2, or 3+; none reference).

** Veteran Integrated Service Networks (VISNs) 13 and 14 are excluded in all these models.

Gebregziabher et al.

Gebregziabher et al. BMC Medical Research Methodology 2012 12:163   doi:10.1186/1471-2288-12-163

Open Data