Table 5.
Results from analyses assessing effect modification.
| Estimateb (95 % CI) |
p-value for interaction | |
|---|---|---|
|
| ||
| Intent-to-treat framework, indoor PM2.5a | ||
| Navajo Nation homes | 0.05 | |
| Placebo (n = 35) | Reference | |
| Education (n = 38) | 37.4 (−26.4, 156.4) | |
| Filtration (n = 33) | −23.7 (−60.3, 46.8) | |
| Nez Perce Tribe homes | ||
| Placebo (n = 33) | Reference | |
| Education (n = 32) | −34.3 (−66.3, 28.3) | |
| Filtration (n = 40) | −67.8 (−82.9, −39.4) | |
| Home square m < 110 | 0.90 | |
| Placebo (n = 42) | Reference | |
| Education (n = 34) | 6.2 (−43.2, 93.6) | |
| Filtration (n = 42) | −46.8 (−70.7, −3.1) | |
| Home square m 110+ | ||
| Placebo (n = 26) | Reference | |
| Education (n = 36) | −8.8 (−54.4, 82.2) | |
| Filtration (n = 31) | −54.9 (−78.0, −7.5) | |
| Resident smokes (yes) | 0.98 | |
| Placebo (n = 21) | Reference | |
| Education (n = 22) | −6.2 (−58.5, 111.9) | |
| Filtration (n = 15) | −47.0 (−78.3, 29.4) | |
| Resident smokes (no) | ||
| Placebo (n = 47) | Reference | |
| Education (n = 48) | −3.2 (−44.1, −67.6) | |
| Filtration (n = 58) | −49.8 (−70.5, −14.4) | |
| Burn level: none/light | 0.44 | |
| Placebo (n = 16) | Reference | |
| Education (n = 17) | 13.6 (−47.1, 143.8) | |
| Filtration (n = 15) | −62.9 (−83.2, −17.9) | |
| Burn level: average | ||
| Placebo (n = 42) | Reference | |
| Education (n = 40) | −12.4 (−48.8, 49.8) | |
| Filtration (n = 42) | −47.4 (−69.4, −9.7) | |
| Burn level: heavy | ||
| Placebo (n = 10) | Reference | |
| Education (n = 12) | 16.0 (−53.5, 189.0) | |
| Filtration (n = 16) | −39.5 (−75.4, 48.9) | |
| Stove age 0 to 10 years | 0.99 | |
| Placebo (n = 31) | Reference | |
| Education (n = 16) | 1.4 (−55.7, 132.0) | |
| Filtration (n = 27) | −49.9 (−76.0, 4.7) | |
| Stove 11+ years | ||
| Placebo (n = 37) | Reference | |
| Education (n = 54) | −5.8 (−47.4, 68.8) | |
| Filtration (n = 46) | −51.2 (−73.4, −10.8) | |
| Stove grade high quality | 0.33 | |
| Placebo (n = 1) | Reference | |
| Education (n = 12) | −51.6 (−96.0, 477.8) | |
| Filtration (n = 8) | −87.2 (−99.0, 57.0) | |
| Stove grade med quality | ||
| Placebo (n = 33) | Reference | |
| Education (n = 32) | 1.5 (−49.0, 102.0) | |
| Filtration (n = 32) | −56.0 (−78.2, −11.2) | |
| Stove grade low quality | ||
| Placebo (n = 24) | Reference | |
| Education (n = 19) | −17.5 (−65.8, 99.0) | |
| Filtration (n = 24) | −30.1 (−69.5, 60.4) | |
| Wood collection prior to burning: | 0.11 | |
| <1 month | ||
| Placebo (n = 25) | Reference | |
| Education (n = 28) | 43.4 (−31.8, 201.5) | |
| Filtration (n = 33) | −45.1 (−73.0, 11.7) | |
| 1 to 6 months | ||
| Placebo (n = 28) | Reference | |
| Education (n = 33) | 9.2 (−44.0, 112.9) | |
| Filtration (n = 26) | −40.0 (−71.4, 25.8) | |
| 6+ months | ||
| Placebo (n = 15) | Reference | |
| Education (n = 9) | −68.0 (−89.7, −0.1) | |
| Filtration (n = 14) | −72.8 (−90.1, −25.5) | |
| Primary wood collection method: | 0.02 | |
| Self-harvested | ||
| Placebo (n = 17) | Reference | |
| Education (n = 20) | 44.0 (−39.1, 240.5) | |
| Filtration (n = 13) | −17.8 (−69.0, 117.7) | |
| Purchase | ||
| Placebo (n = 18) | Reference | |
| Education (n = 16) | 40.1 (−43.2, 245.9) | |
| Filtration (n = 21) | −42.7 (−75.1, 31.7) | |
| Wood delivery program | ||
| Placebo (n = 33) | Reference | |
| Education (n = 30) | −35.1 (−66.6, 26.0) | |
| Filtration (n = 37) | −68.6 (−83.3, −40.9) | |
| Intent-to-treat framework, indoor PM2.5c | ||
| Participant age 50 to 68 | 0.56 | |
| Placebo (n = 38) | Reference | |
| Education (n = 31) | −9.2 (−52.5, 73.8) | |
| Filtration (n = 36) | −58.8 (−78.0, 22.9) | |
| Participant age 69+ | ||
| Placebo (n = 33) | Reference | |
| Education (n = 38) | 7.3 (−42.8, 101.3) | |
| Filtration (n = 39) | −38.9 (−67.4, 14.7) | |
| Female participant | 0.57 | |
| Placebo (n = 48) | Reference | |
| Education (n = 51) | 12.3 (−35.0, 93.9) | |
| Filtration (n = 49) | −49.9 (−71.2, −12.8) | |
| Male participant | ||
| Placebo (n = 24) | Reference | |
| Education (n = 20) | −23.6 (−65.8, 70.8) | |
| Filtration (n = 26) | −50.6 (−77.2, 7.0) | |
| Intent-to-treat framework, personal PM2.5d | ||
| Home square m < 110 | 0.35 | |
| Placebo (n = 17) | Reference | |
| Education (n = 12) | 4.3 (−66.8, 227.8) | |
| Filtration (n = 15) | −51.8 (−82.9, 35.4) | |
| Home square m 110+ | ||
| Placebo (n = 18) | Reference | |
| Education (n = 25) | −41.2 (−76.8, 48.9) | |
| Filtration (n = 23) | −36.2 (−75.3, 64.8) | |
| Resident smokes (yes) | 0.08 | |
| Placebo (n = 21) | Reference | |
| Education (n = 20) | −16.5 (−65.9, 104.2) | |
| Filtration (n = 16) | 11.8 (−56.1, 184.9) | |
| Resident smokes (no) | ||
| Placebo (n = 14) | Reference | |
| Education (n = 17) | −54.8 (−84.0, 27.3) | |
| Filtration (n = 22) | −68.4 (−88.1, −15.9) | |
| Stove age 0 to 10 years | 0.09 | |
| Placebo (n = 11) | Reference | |
| Education (n = 8) | −21.0 (−80.7, 224.2) | |
| Filtration (n = 10) | −76.6 (−93.8, −12.0) | |
| Stove 11+ years | ||
| Placebo (n = 24) | Reference | |
| Education (n = 29) | −34.3 (−71.8, 53.0) | |
| Filtration (n = 28) | −24.5 (−67.2, 73.9) | |
PM2.5 = fine particulate matter; CI = confidence interval; m = meter.
a
Model adjusted for baseline (Winter 1) outcome; model includes nested random term: home:cohort:area.
b
Estimate and 95 % Confidence Intervals reported as percent differences in geometric mean PM2.5.
c
Model adjusted for baseline (Winter 1) outcome; model includes nested random term: participant:home:cohort:area.
d
Model only includes data from Nez PerceTribe study area; adjusted for baseline (Winter 1) outcome; model includes nested random term: participant:home:cohort.