Table 1
Baseline characteristics by primary stove type for 299 Nepali women, Kaski District, Nepal.
| All Stoves (N = 299) | LPG (N = 195) | Biogas (N = 35) | Wood (N = 69) | X2 value across stove types | |
|---|---|---|---|---|---|
| N (%) | N (%) | N (%) | N (%) | P value | |
| Age categories (years) | |||||
| 40 to <45 | 35 (12%) | 23 (12%) | 3 (9%) | 9 (13%) | |
| 45 to <50 | 54 (18%) | 38 (19%) | 8 (23%) | 8 (12%) | |
| 50 to <55 | 78 (26%) | 53 (27%) | 10 (29%) | 15 (22%) | |
| 55 to <60 | 55 (18%) | 36 (18%) | 7 (20%) | 12 (17%) | |
| 60 to <65 | 48 (16%) | 33 (17%) | 3 (9%) | 12 (17%) | |
| 65 to <70 | 29 (10%) | 12 (6%) | 4 (11%) | 13 (19%) | 0.20 |
| Marital status | |||||
| Married | 247 (83%) | 162 (84%) | 27 (77%) | 58 (84%) | |
| Single | 2 (1%) | 2 (1%) | 0 (0%) | 0 (0%) | |
| Widow | 47 (16%) | 28 (14%) | 8 (23%) | 11 (16%) | |
| Divorced | 2 (1%) | 2 (1%) | 0 (0%) | 0 (0%) | 0.73 |
| Monthly income (Nepalese Rupee) | |||||
| <8 K | 27 (9%) | 10 (5%) | 2 (6%) | 15 (22%) | |
| 8–16 K | 36 (12%) | 18 (9%) | 4 (11%) | 14 (20%) | |
| 16–32 K | 90 (30%) | 57 (29%) | 15 (43%) | 17 (25%) | |
| 32–64 K | 63 (21%) | 47 (24%) | 8 (23%) | 7 (10%) | |
| >64 K | 33 (11%) | 27 (14%) | 1 (3%) | 5 (7%) | |
| Refuse/DNK | 52 (17%) | 36 (18%) | 5 (14%) | 11 (16%) | 0.00 |
| Living location | |||||
| Urban | 177 (59%) | 155 (79%) | 16 (46%) | 6 (9%) | |
| Rural | 122 (41%) | 40 (21%) | 19 (54%) | 63 (91%) | 0.00 |
| Education | |||||
| No formal education | 171 (57%) | 99 (51%) | 17 (49%) | 55 (80%) | |
| Any primary | 60 (20%) | 38 (20%) | 13 (37%) | 9 (13%) | |
| Any secondary | 57 (19%) | 49 (25%) | 4 (11%) | 4 (6%) | |
| Greater than secondary education | 10 (3%) | 8 (4%) | 1 (3%) | 1 (1%) | 0.00 |
| Read & write Nepali | 131 (44%) | 94 (48%) | 21 (60%) | 16 (23%) | 0.00 |
| Smoking history | |||||
| Never | 205 (69%) | 143 (73%) | 25 (71%) | 37 (54%) | |
| Current | 46 (15%) | 24 (12%) | 6 (17%) | 16 (23%) | |
| Ex-Smoker | 48 (16%) | 28 (14%) | 4 (11%) | 16 (23%) | 0.04 |
| Alcohol history | |||||
| Don’t drink | 193 (65%) | 118 (61%) | 27 (77%) | 48 (70%) | |
| Occasional Drink | 71 (24%) | 56 (29%) | 4 (11%) | 11 (16%) | |
| >1 drink/week for >6 months | 35 (12%) | 21 (11%) | 4 (11%) | 10 (14%) | 0.08 |
| BMI categories | |||||
| Underweight (<19 kg/m2) | 12 (4%) | 5 (3%) | 0 (0%) | 7 (10%) | |
| Normal (19–25 kg/m2) | 114 (38%) | 63 (32%) | 18 (51%) | 33 (48%) | |
| Overweight (25–30 kg/m2) | 109 (36%) | 72 (37%) | 12 (34%) | 25 (36%) | |
| Obese (30–39 kg/m2) | 62 (21%) | 53 (27%) | 5 (14%) | 4 (6%) | |
| Extreme Obesity (>39 kg/m2) | 2 (1%) | 2 (1%) | 0 (0%) | 0 (0%) | 0.00 |
| Hypertension | |||||
| No | 194 (65%) | 124 (64%) | 25 (71%) | 45 (65%) | |
| Known diagnosis | 64 (21%) | 46 (24%) | 7 (20%) | 11 (16%) | |
| Measured BP ≥ 140/90 mm/Hg | 41 (14%) | 25 (13%) | 3 (9%) | 13 (19%) | 0.43 |
| Diabetes | |||||
| No | 241 (81%) | 149 (76%) | 32 (91%) | 60 (87%) | |
| Known diagnosis | 24 (8%) | 21 (11%) | 0 (0%) | 3 (4%) | |
| Measured HbA1c ≥ 6.5% | 34 (11%) | 25 (13%) | 3 (9%) | 6 (9%) | 0.09 |
[i] Abbreviations: BMI = body mass index; BP = blood pressure; HbA1c = hemoglobin A1c.
Table 2
Subclinical cardiovascular outcomes with an unadjusted bivariate analysis across 3 primary stove types.
| All Stoves | LPG Stoves | Biogas Stoves | Wood Stoves | All Stoves | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| N | Mean or % value | SD | Mean or % value | SD | Mean or % value | SD | Mean or % value | SD | p-value | |
| Left ventricular systolic function | ||||||||||
| Mean biplane ejection fraction | 294 | 61.6 | 5.9 | 61.4 | 5.9 | 61.6 | 6.7 | 62.2 | 5.7 | 0.62 |
| Mean LV mass/BSA (g/m2) | 298 | 68.0 | 16.5 | 67.9 | 16.6 | 68.5 | 16.2 | 68.1 | 16.4 | 0.98 |
| Mean LV systolic volume/BSA (mL/m2) | 294 | 21.1 | 5.6 | 21.1 | 5.5 | 20.7 | 6.6 | 21.5 | 5.2 | 0.79 |
| Mean LV diastolic volume/BSA (mL/m2) | 292 | 55.2 | 12.6 | 54.7 | 11.7 | 53.8 | 14.0 | 57.4 | 14.0 | 0.24 |
| Left ventricular diastolic function | ||||||||||
| Normal diastolic function, % | 284 | 95% | – | 97% | – | 91% | – | 91% | – | 0.14 |
| Mean left atrial volume/BSA (mL/m2) | 292 | 21.3 | 6.0 | 20.8 | 6.0 | 20.4 | 5.6 | 23.0 | 5.7 | 0.03 |
| Pulmonary Pressure | ||||||||||
| Mean pulmonary artery systolic pressure (mmHg) | 185 | 25.9 | 13.4 | 25.4 | 11.1 | 24.1 | 10.3 | 28.2 | 19.2 | 0.40 |
| Pulmonary hypertension (PASP > 35 mmHg) present, % | 299 | 42% | – | 44% | – | 37% | – | 41% | – | 0.70 |
| Right ventricular function | ||||||||||
| Mean tricuspid annulus S’ velocity (cm/s) | 215 | 11.1 | 1.5 | 11.1 | 1.5 | 11.0 | 1.5 | 11.2 | 1.5 | 0.94 |
| Mean RV size (mm) | 297 | 35.0 | 4.4 | 35.0 | 4.3 | 34.1 | 4.5 | 35.2 | 4.7 | 0.44 |
| Significant Valvular Disease*, % | 299 | 14% | – | 13% | – | 9% | – | 20% | 0.20 | |
| Blood Pressure | ||||||||||
| Mean systolic blood pressure (mmHg) | 299 | 119.4 | 18.6 | 119.7 | 17.5 | 119.3 | 23.4 | 118.6 | 19.4 | 0.92 |
| Mean diastolic blood pressure (mmHg) | 299 | 79.6 | 11.5 | 79.8 | 11.3 | 79.8 | 14.1 | 78.9 | 10.5 | 0.85 |
| Hypertension (≥140/90 mmHg), % | 299 | 35% | – | 36% | – | 29% | – | 35% | – | 0.66 |
| Electrocardiogram | ||||||||||
| Mean Q-T interval (ms) | 299 | 413.9 | 25.0 | 414.0 | 25.9 | 408.0 | 20.3 | 416.5 | 24.4 | 0.26 |
| Q waves present, % | 299 | 9% | – | 7% | – | 14% | – | 10% | – | 0.38 |
| ST depression present, % | 299 | 4% | – | 4% | – | 9% | – | 3% | – | 0.41 |
| ST elevation present, % | 299 | 7% | – | 5% | – | 9% | – | 13% | – | 0.07 |
| T-wave abnormal, % | 299 | 14% | – | 15% | – | 9% | – | 14% | – | 0.53 |
| ST/T-wave abnormality**, % | 299 | 23% | – | 21% | – | 26% | – | 28% | – | 0.51 |
| Mean ankle-brachial index | 299 | 1.1 | 0.1 | 1.2 | 0.1 | 1.1 | 0.1 | 1.1 | 0.1 | 0.05 |
[i] Abbreviations: LV = left ventricle; BSA = body surface area; RV = right ventricle; PASP = pulmonary artery systolic pressure.
* Significant valvular disease: any degree of stenosis of any cardiac valve, any aortic regurgitation, or greater than mild tricuspid or mitral regurgitation.
** ST/T-wave abnormalities: composite of ST-segment depressions, elevations or T-wave abnormalities.
Table 3
Multivariate linear regression results for the use of biogas and wood stoves vs. liquified petroleum gas (LPG) stoves for a series of different cardiovascular outcomes.
| Biogas Stove β (95% CI)a | P-value | Wood Stove β (95% CI)a | P-value | |
|---|---|---|---|---|
| Left ventricular mass indexed to BSA (g/m2) | 0.90 (–5.52, 7.32) | 0.78 | –0.96 (–7.06, 5.13) | 0.76 |
| Left ventricular end diastolic volume indexed to BSA (mL/m2) | 2.34 (–2.60, 7.29) | 0.35 | 7.97 (3.11, 12.83) | 0.001 |
| Left ventricular end systolic volume, indexed to BSA (mL/m2) | 0.54 (–1.87, 2.95) | 0.66 | 1.90 (–0.12, 3.93) | 0.07 |
| Left ventricular ejection fraction, % | 0.84 (–1.85, 3.53) | 0.54 | 1.74 (–0.65, 4.13) | 0.15 |
| Pulmonary artery systolic pressure (mmHg) | –7.62 (–21.69, 6.45) | 0.29 | –0.45 (–14.23, 13.34) | 0.95 |
| Right ventricular basal diameter (mm) | –1.66 (–4.10, 0.78) | 0.18 | –0.37 (–3.26, 2.53) | 0.80 |
| Right ventricular mean tricuspid annulus S’ velocity (cm/s) | 7.52 (–7.83, 22.88) | 0.34 | 4.31 (–10.33, 18.95) | 0.56 |
| Left atrial volume indexed to body surface area (mL/m2) | 0.44 (–1.64, 2.51) | 0.68 | 3.15 (1.22, 5.09) | 0.001 |
| ABI | –0.02 (–0.05, 0.00) | 0.10 | –0.01 (–0.04, 0.02) | 0.43 |
| QT interval (ms) | –4.91 (–13.07, 3.26) | 0.24 | –0.52 (–9.30, 8.27) | 0.91 |
| Systolic BP | 2.19 (–6.15, 10.52) | 0.61 | –1.52 (–8.56, 5.52) | 0.67 |
| Diastolic BP | 0.75 (–4.45, 5.95) | 0.78 | –1.60 (–6.19, 2.98) | 0.49 |
[i] Abbreviations: BSA = body surface area; ABI = ankle brachial index; BP = blood pressure.
a Adjusted for age, BMI or BSA, education, diabetes, smoking history, urban/rural residence, presence of house heating, and fuel use for lighting.
Table 4
Multivariate unconditional logistic regression analyses evaluating associations of primary stove type (wood or biogas vs. liquid petroleum gas) with changes in ECG outcomes.
| ECG characteristic (Minnesota code) | Biogas Stove Odds ratio (95% CI)a | P-value | Wood Stove Odds ratio (95% CI)a | P-value |
|---|---|---|---|---|
| Q waves present (1-1-1, 1-1-2, 1-1-3, 1-1-4) | 3.26 (0.83, 12.79) | 0.09 | 3.11 (0.78, 12.45) | 0.11 |
| ST depression present (4-1-1, 4-1-2, 4-2) | 3.97 (0.80, 19.82) | 0.09 | 1.01 (0.19, 5.26) | 0.99 |
| ST elevation present (9-2) | 1.95 (0.38, 9.97) | 0.42 | 1.46 (0.37, 5.70) | 0.59 |
| T-wave abnormality present (5-1, 5-2, 5-3) | 0.40 (0.10, 1.52) | 0.18 | 0.43 (0.15, 1.26) | 0.12 |
| ST/T wave abnormality present (4-1-1, 4-1-2, 4-2, 9-2, 5-1, 5-2, 5-3) | 1.08 (0.40, 2.89) | 0.87 | 0.72 (0.31, 1.67) | 0.45 |
[i] a Adjusted for age, BMI, education, diabetes, smoking history, urban/rural residence, presence of house heating, and fuel use for lighting.