Correlates of PPG ratios selected by stepwise regression
| Parameters | PPG ratio | |||||||
|---|---|---|---|---|---|---|---|---|
| Time intervals (s) | ||||||||
| 0–30 | 30–60 | 60–90 | 90–120 | 120–150 | 150–180 | 180–210 | 210–240 | |
| Regression statistic | ||||||||
| Model R2 (%) | 9.7 | 21.4 | 22.5 | 19.8 | 19.2 | 16.3 | 13.2 | 12.2 |
| Age (+10 years)* | ||||||||
| β±SE | 0.014±0.020 p=0.45 | −0.0007±0.028 p=0.98 | 0.005±0.025 p=0.85 | 0.004±0.019 p=0.85 | 0.007±0.017 p=0.68 | −0.0008±0.014 p=0.95 | 0.004±0.012 p=0.72 | 0.002±0.011 p=0.91 |
| Partial r2 (%) | 0.02 | 0 | 0.01 | 0.04 | 0.06 | 0 | 0.04 | 0.01 |
| Female | ||||||||
| β±SE | 0.16±0.05 p=0.0004 | 0.49±0.68 p<0.0001 | 0.46±0.061 p<0.0001 | 0.35±0.050 p<0.0001 | 0.26±0.041 p<0.0001 | 0.20±0.035 p<0.0001 | 0.14±0.031 p<0.0001 | 0.12±0.03 p<0.0001 |
| Partial r2 (%) | 3.9 | 13.6 | 16.0 | 15.1 | 13.5 | 12 | 7.7 | 6.1 |
| Current smoking (0,1) | ||||||||
| β±SE | −0.30±0.07 p=0.0004 | −0.39±0.09 p<0.0001 | −0.29±0.085 p=0.0007 | – | – | – | – | – |
| Partial r2 (%) | 4.0 | 3.7 | 3.1 | – | – | – | – | – |
| Body mass index (+1 kg/m²) | ||||||||
| β±SE | −0.014±0.007 p=0.017 | −0.027±0.009 p=0.003 | −0.032±0.008 p<0.0001 | −0.025±0.007 p<0.0001 | −0.022±0.005 p<0.0001 | −0.018±0.005 p<0.0001 | −0.015±0.004 p=0.0002 | −0.013±0.004 p=0.0008 |
| Partial r2 (%) | 1.7 | 3.0 | 3.4 | 3.4 | 4.5 | 4.5 | 4.1 | 3.5 |
| Total cholesterol (+1 mmol/L) | ||||||||
| β±SE | – | −0.068±0.034 p=0.045 | – | – | – | – | – | – |
| Partial r2 (%) | – | 1.1 | – | – | – | – | – | – |
| Blood glucose (+1 mmol/L) | ||||||||
| β±SE | 0.10±0.04 p=0.013 | – | – | 0.07±0.04 p=0.026 | 0.06±0.03 p=0.034 | – | 0.05±0.02 p=0.027 | 0.06±0.02 p=0.006 |
| Partial r2 (%) | 1.9 | – | – | 1.3 | 1.2 | – | 1.4 | 2.2 |
Values are mutually adjusted partial regression coefficients ±SE. *Age was forced into all models. The covariables considered in stepwise models included sex, systolic and diastolic blood pressures, heart rate, body mass index, current smoking, total cholesterol, LDL cholesterol, haematocrit, blood glucose, antihypertensive and lipid-lowering drug treatment, and history of ischaemic heart disease.
LDL, low-density lipoprotein; PPG, photoplethysmography.