Table 3.
Linear regression analysis of MHR(beats/min) and its changes during 20 years (dependent variables) in relation to baseline (year 0 or year 7) variables and their changes. A. Cross-sectional and change in MHR on baseline levels
| Year 0 cross section | MHR (Year 7-Year 0) regressed on Year 0 variables | MHR (Year 20-Year 7) regressed on Year 7 variables | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Variable (year 0 or year 7) | Slope | SE | P-value | Slope | SE | P-value | Slope | SE | P-value |
| Intercept | 180 | 6.88 | <.0001 | 31 | 8.93 | 0.0001 | 20 | 9.87 | 0.04 |
| Age (years) | −0.17 | 0.07 | 0.01 | −0.14 | 0.08 | 0.08 | −0.12 | 0.09 | 0.20 |
| Gender (women) | −2.89 | 0.74 | 0.0001 | −2.93 | 0.97 | 0.003 | 2.21 | 1.04 | 0.03 |
| Race (black) | −3.05 | 0.58 | <.0001 | −1.78 | 0.74 | 0.02 | 1.97 | 0.84 | 0.02 |
| BMI (kg/m2) | −0.31 | 0.05 | <.0001 | −0.20 | 0.07 | 0.003 | −0.18 | 0.07 | 0.005 |
| Height (m) | −0.11 | 0.04 | 0.01 | −0.02 | 0.05 | 0.77 | −0.001 | 0.06 | 0.99 |
| Pre-exercise heart rate (beats/min) | 0.23 | 0.02 | <.0001 | −0.14 | 0.02 | <.0001 | −0.16 | 0.02 | <.0001 |
| Systolic Blood Pressure (mmHg) | 0.06 | 0.02 | 0.02 | −0.05 | 0.03 | 0.13 | −0.09 | 0.03 | 0.01 |
| Forced vital capacity (L)* | 2.58 | 0.45 | <.0001 | −0.94 | 0.58 | 0.11 | −0.34 | 0.62 | 0.59 |
| Physical activity score (100 exercise units) | 0.38 | 0.08 | <.0001 | −0.01 | 0.10 | 0.91 | −0.2 | 0.1 | 0.17 |
| TV watching (hours/week)† | −0.11 | 0.02 | <.0001 | −0.04 | 0.03 | 0.23 | 0.09 | 0.04 | 0.01 |
| Smoking status (vs. never) | |||||||||
| Current | −8.07 | 0.53 | <.0001 | 0.79 | 0.71 | 0.27 | 1.93 | 0.86 | 0.03 |
| Former | −1.87 | 0.68 | 0.006 | −1.65 | 0.93 | 0.07 | 1.88 | 1.16 | 0.11 |
| R2 | 0.22 | 0.05 | 0.06 | ||||||
| B. Concurrent changes | ||||||
|---|---|---|---|---|---|---|
| MHR (Year 7-Year 0) regressed on change in variables (Year 7-Year 0)‡ | MHR (Year 20-Year 7) regressed on change in variables (Year 20-Year 7)‡ | |||||
| Variable | Slope | StdErr | P-value | Slope | StdErr | P-value |
| Intercept | 0.46 | 0.61 | 0. 46 | −9.52 | 0.77 | <.0001 |
| ΔBMI ( kg/m2) | −0.36 | 0.11 | 0.001 | −0.18 | 0.07 | 0.008 |
| ΔPre-exercise heart rate (beats/min) | 0.17 | 0.02 | <.0001 | 0.11 | 0.02 | <.0001 |
| ΔSystolic Blood Pressure (mmHg) | 0.13 | 0.03 | <.0001 | 0.02 | 0.03 | 0.40 |
| ΔFVC (L)* | 3.86 | 1.07 | 0.0003 | −0.44 | 1.03 | 0.67 |
| ΔPhysical activity score (exercise units) | 0.001 | 0.001 | 0.19 | 0.002 | 0.001 | 0.20 |
| ΔTV watching (hours/week)† | −0.04 | 0.03 | 0.17 | −0.08 | 0.03 | 0.01 |
| ΔSmoking status (vs. never) | ||||||
| Long term former | −1.11 | 0.91 | 0.22 | 0.30 | 0.94 | 0.75 |
| Recent quitter | 2.09 | 1.29 | 0.10 | 0.11 | 1.40 | 0.94 |
| Consistently current | 0.53 | 0.82 | 0.52 | −2.37 | 1.03 | 0.02 |
| Recent starter | −5.85 | 1.73 | 0.0008 | −3.95 | 2.25 | 0.08 |
| R2 | 0.08 | 0.06 | ||||
*
Since year 7 lung function data were not collected, year 10 lung function data were used in the analysis when baseline was year 7.
†
Year 5 data were used in the analysis when baseline was year 0; year 10 data were used when baseline was year 7.
‡
Gender and race were included as covariates in the models of change in MHR on change in other characteristics. Coefficients are not shown, but are similar to those given for models of change in MHR on baseline levels of other characteristics.