Table 3 Studies examining disease severity (N = 8)
Study, Year, Country | Design and Population | Smoke Exposure | Outcome | Results | Bias Assessment |
|---|---|---|---|---|---|
Risk of hospitalization among premature children with RSV illness | |||||
Groothuis et al., 1988 US [32] | Prospective cohort study of 30 premature infants aged <2 years with BPD receiving home oxygen therapy; participants followed for 5 mos (Dec-Apr) | Smokers in home | Risk of hospitalization (11 of 16 with RSV hospitalized) vs. outpatient treatment | NS; bivariate analysis reported and P value not given | No multivariate analysis performed (confounding bias) |
Risk of hospitalization among children in the general population with RSV illness | |||||
Al-Shehri 2005 Saudi Arabia [33] | Case–control study; 51 children aged ≤5 years hospitalized for bronchiolitis (cases) and 115 children with bronchiolitis but not hospitalized (controls); 40% of cases were RSV | History of exposure to smoking | Risk of hospitalization vs. outpatient treatment for bronchiolitis | aOR, 2.51 (95% CI, 2.11–3.73); P = 0.05 | Risk of participant selection bias because both cases and controls had bronchiolitis |
Hall 2009 US [2] | 919 children aged <5 years with laboratory-confirmed RSV infections | Smoking in household | Risk of hospitalization vs. outpatient treatment | NS in multivariate analysis (no aOR, CI, or P value)NS in bivariate analysis (P = 0.43) | No significant bias concerns affecting the relationship of ETS and outcome |
|  |  | Mother smokes | Risk of hospitalization vs. outpatient treatment | Not included in multivariate analysis NS in bivariate analysis (P = 0.21) |  |
Somech 2006 Canada [34] | Prospective study of 195 infants (mean age 3.8 months) with laboratory-confirmed RSV infection | Exposure to smoke from at least one family member | Hospitalization (113) vs. outpatient treatment (82) of RSV | ETS exposure was unrelated to hospitalization (P value not reported) | No multivariate analysis performed (confounding bias) |
Disease severity in children in the general population hospitalized with RSV illness | |||||
Al-Sonboli 2006 Yemen [35] | Prospective study of 325 children aged ≤2 with acute respiratory illness seeking emergency or outpatient services at a hospital (82% RSV) | Smoking in household | Severe hypoxia among RSV-positive group | aOR, 3.8 (95% CI, 1.5–9.8); P = 0.002 | No description of how smoke exposure or other family characteristics were ascertained (exposure bias) |
Bradley 2005 US [36] | Prospective evaluation of 206 infants hospitalized with their first episode of severe RSV bronchiolitis | Current maternal smokingMaternal smoking status during pregnancy | Lowest oxygen saturation rate | Current maternal smoking was associated with lower oxygen saturation, P =0.05No effect of smoking during pregnancy only (n = 10) | No significant bias concerns affecting the relationship of ETS and outcome |
Chatzimichael 2007 Greece [37] | Prospective study of 240 children aged 6–24 months hospitalized for bronchiolitis | Exposure to >5 cigarettes per day in the home; children with prenatal exposure were excluded | Disease severity measured with a clinical rating tool that included hypoxemia | aOR, 2.2 (95% CI, 1.1–3.6); P = 0.003 | Unclear RSV disease classification; severity tool used |
Sritippayawan 2006 Thailand [38] | Study of 19 children (median age 9 months) admitted to the hospital with laboratory-confirmed RSV LRTI | Exposure measured by urinary cotinine | Hypoxemia (oxygen saturation <92%) | Cotinine was detected in 100% of infants with hypoxia vs. 33% of those without hypoxia; P = 0.01 | High risk of selective reporting biasRisk of confounding not clear; regression analysis appears to have been performed but was insufficiently reported so it was not possible to tell which factors were controlled for |