Results
Four hundred seventy-one patients hospitalized with diagnoses of acute
bronchiolitis were initially included in the study. However, 31 patients
were subsequently excluded, 16 diagnosed with congenital heart disease,
four with metabolic disease, three with histories of sibling deaths, and
eight whose families declined to take part. Four hundred forty patients
aged between one and 24 months were thus finally enrolled.
Two hundred seventy-seven (63%) of the 440 patients were boys, and 163
(37%) were girls. The mean age of the patients was 6.16±4.99 months.
Patients were divided into two groups, severe bronchiolitis (85
patients) and mild-moderate bronchiolitis (355 patients). No difference
was determined between the two groups in terms of age or sex, although
weight-for-age z-scores were significantly lower in the severe
bronchiolitis group compared to the mild-moderate bronchiolitis group
(p<0.001). No significant differences were observed between
the two groups in terms of birth week, cesarean delivery, receipt of
mother’s milk only, atopic disease, GERD, or history of admission to the
NICU. However, attack numbers were significantly higher in the severe
bronchiolitis group than in the mild-moderate group (Table 1).
No statistically significant difference was determined between the two
groups in terms of parental histories of asthma (p=0.240). No
significant difference was also found between the groups in terms of
maternal histories of smoking during pregnancy and paternal active
smoking histories, although the proportion of mothers with active
smoking histories was significantly higher in the severe bronchiolitis
group (20%) than in the mild-moderate bronchiolitis group (11.3%)
(p=0.050, p=0.617, and p=0.046, respectively). No significant difference
was observed between the two groups in terms of maternal education
levels, but paternal education levels were lower in the severe
bronchiolitis group (p=0.414 and p=0.028, respectively). No significant
difference was also observed between the two groups in terms of place
and type of residence, and type of heating employed. A history of being
the only child in the home was significantly lower in the severe group
than in the mild-moderate group (p=0.010), while the number of
individuals in the household was higher in the severe group than in the
mild-moderate group (p=0.011) (Table 2).
Feeding was lower, subcostal retraction and cyanosis were more common,
times between onset of symptoms and worsening of findings and
presentation to hospital were shorter, oxygen saturation was lower, HFNC
and intubation requirements were more frequent, and hospital stays were
longer in the severe bronchiolitis group compared to the mild-moderate
bronchiolitis group (Table 3).
Mean Hb values were 10.83±1.47 g/dL in the severe bronchiolitis group
and 11.19±1.21 g/dL in the mild-moderate bronchiolitis group (p=0.021).
Mean absolute neutrophil count was 5.34±4.45 /mm3 in
the severe bronchiolitis group and 4.38±3.32 /mm3 in
the mild-moderate group (p=0.004). CRP values were 1.74±2.78 mg/dL in
the severe bronchiolitis group and 0.96±1.79 mg/dL in the mild-moderate
group (p=0.002).
Each demographic, clinical, and laboratory variable of the patients
included in the study was individually subjected to univariate logistic
regression analysis in order to identify parameters potentially
associated with the development of bronchiolitis. Accordingly,
weight-for-age z-score, time between onset of symptoms and admission,
time between onset of symptoms and worsening of findings, number of
previous bronchiolitis attacks, history of maternal smoking during
pregnancy, history of maternal active smoking, being an only child,
number of individuals in the household, decreased feeding, hemoglobin
levels, absolute neutrophil count, lymphocyte count, and CRP emerged as
significant at the p <0.05 level. The above parameters
emerging as significant at univariate logistic regression analysis were
than subjected to multivariate logistic regression analysis (backward LR
model). Parameters identified at multivariate logistic regression
analysis such as a low weight-for-age z-score, a short time between
onset of symptoms and admission, a higher number of previous attacks,
and low hemoglobin emerged as independent predictors of severe
bronchiolitis development. Low weight-for-age z-score was found to
increase the risk of severe bronchiolitis development 0.56-fold (CI:
0.409 – 0.760), a short time between onset of symptoms and admission
increased the risk 0.62-fold (CI: 0.519 – 0.735), previous history of
frequent bronchiolitis attacks increased the risk 1.84-fold (CI: 1.135
– 2.968), and low hemoglobin levels increased the risk 0.72-fold (CI:
0.537 – 0.969) (Table 4).