Table 2. Selected regression models describing direct and indirect associations between health factors.
| Explanatory variable | Dependent variable (outcome for each model) | |||||
|---|---|---|---|---|---|---|
| SOB, OR (95% CI) |
Fatigue, OR (95% CI) |
Pain, OR (95% CI) |
Anxiety or depression, OR (95% CI) |
Functional limitations, OR (95% CI) |
Patient-rated health, relative mean difference (95% CI) |
|
| Age (per year) | 1.01 (1.01, 1.02) | 1.02 (1.01, 1.03) | 1.01 (1.01, 1.02) | 0.99 (0.98, 0.99) | 1.02 (1.01, 1.03) | −0.08 (−0.13, −0.04) |
| Women | 3.48 (1.72, 7.03) | 1.39 (1.25, 1.54) | 1.61 (1.46, 1.78) | 1.17 (1.06, 1.30) | ||
| Single | −1.58 (−2.33, −0.83) | |||||
| Body mass index | 1.04 (1.03, 1.05) | 1.02 (1.02, 1.03) | 1.04 (1.03, 1.05) | |||
| Current smoker | 1.19 (1.01, 1.39) | 1.26 (1.09, 1.47) | 1.40 (1.21, 1.62) | 1.21 (1.05, 1.39) | ||
| Haemoglobin | 0.93 (0.90, 0.96) | 0.94 (0.91, 0.97) | 0.90 (0.88, 0.93) | 0.95 (0.93, 0.98) | ||
| Heart failure ≥ 6 months | 1.39 (1.25, 1.54) | 1.23 (1.11, 1.36) | 1.18 (1.07, 1.30) | −1.33 (−2.08, −0.58) | ||
| Heart rate | 1.01 (1.01, 1.01) | 1.01 (1.00, 1.01) | −0.05 (−0.08, −0.03) | |||
| Beta blocker | ||||||
| ACEi or ARB | 0.70 (0.59, 0.82) | |||||
| Diuretic | 1.94 (1.67, 2.24) | 1.61 (1.41, 1.85) | 1.29 (1.15, 1.44) | 1.40 (1.25, 1.57) | 1.34 (1.18, 1.52) | −1.42 (−2.35, −0.49) |
| Device | 1.26 (1.09, 1.45) | |||||
| Cardiology | 0.82 (0.74, 0.92) | 1.28 (0.54, 2.03) | ||||
| Inpatient | 1.35 (1.20, 1.51) | 1.44 (1.29, 1.60) | 1.24 (1.11, 1.37) | 1.28 (1.15, 1.44) | −2.04 (−2.87, −1.21) | |
| Comorbidities | ||||||
| Ischemic heart disease | 1.25 (1.14, 1.38) | 1.20 (1.09, 1.32) | ||||
| Atrial fibrillation | 1.16 (1.06, 1.27) | |||||
| Hypertension | ||||||
| Dilated cardiomyopathy | ||||||
| Valve surgery | ||||||
| Diabetes | 1.17 (1.03, 1.32) | 1.27 (1.13, 1.42) | −1.33 (−2.20, −0.47) | |||
| COPD | 1.84 (1.62, 2.10) | 1.69 (1.50, 1.91) | 1.34 (1.19, 1.52) | 1.21 (1.08, 1.36) | 1.22 (1.08, 1.38) | |
| Chronic kidney disease* | 1.23 (1.10, 1.38) | 1.24 (1.12, 1.38) | ||||
| Ejection fraction <40% | ||||||
| Symptoms** | ||||||
| Shortness of breath | 1.98 (1.74, 2.26) | −6.24 (−7.30, −5.18) | ||||
| Fatigue | 2.45 (2.16, 2.79) | −5.53 (−6.61, −4.45) | ||||
| Pain | 2.33 (2.10, 2.58) | −4.51 (−5.31, 3.71) | ||||
| Anxiety or depression | 10.03 (5.16, 19.50) | −18.68 (−23.22, −14.14) | ||||
| Functional limitations (problems with usual activities) | −7.51 (−8.37, −6.65) | |||||
| Non-linear effects and interactions | ||||||
| Age (per year) and female | 0.99 (0.98, 0.99) | |||||
| Age (per year) and anxiety or depression | 0.98 (0.97, 0.99) | 0.15 (0.08, 0.21) | ||||
The models were built by fitting ordered sequences of logistic or linear regression models for each variable adjusted by all the variables to their left-hand side in the HF health model (Fig 2). Where variables were in domains of multiple outcomes, e.g., symptoms, they were regressed on variables to their left that were not in the same domain. Variables in the same domain or to the right of the outcome variable are noted by grey shading as these would not be relevant for that component of the model. For each outcome, the regression model that best described the data was selected by comparing nested models with different combinations of explanatory variables. Patient-rated health was based on EuroQol visual analogue scale, where patients rate their health from 0 (worst imaginable health state) to 100 (best imaginable health state).
*Defined by estimated glomerular filtration rate < 60 ml/min/1.73 m2.
**Pain, anxiety, and functional limitations were ‘any’ compared to none, and shortness of breath and fatigue were ‘marked or severe’ compared to ‘none or slight’.
ACEi, angiotensin converting enzyme inhibitor; ARB, angiotensin II receptor blocker; COPD; chronic obstructive pulmonary disease.