Variation in Inpatient Diagnostic Testing and Management of Bronchiolitis

METHODS

RESULTS

A total of 17397 patients were included in the analysis. The study sample is described in detail in Table 1. Briefly, the mean age was 3.96 months, and 59% were male. The mean LOS was 2.97 days; 72% received chest radiographs, 45% received antibiotics, and 25% received systemic steroids.

The mean LOS varied considerably across hospitals (range: 2.40–3.90 days; Fig 1), and hospital remained a significant contributor to LOS variation after controlling for our covariates (P < .001). There was significant variation across hospitals in use of diagnostic tests (Fig 2) and medication (Fig 3), and, again, these differences remained significant after controlling for covariates (P < .001). For example, the use of any antibiotics varied from 28% to 62% across hospitals, and the use of chest radiographs varied from 38% to 89%. There were also significant differences across hospitals in readmission rates (Fig 1), varying from 0% to 2.7% across hospitals, and they remained significant after controlling for covariates, including LOS (P < .001). In addition, longer LOSs were associated with decreased likelihood of readmission. Compared with children who were discharged with an LOS of 1 day, children with LOS of 2 days (odds ratio [OR]: 0.49; 95% confidence interval [CI]: 0.37 to 0.66), 3 days (OR: 0.41; 95% CI: 0.25 to 0.68), or 4 or more days (OR: 0.29; 95% CI: 0.19 to 0.46), all were significantly less likely to be readmitted.

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Fig 1.

Distribution of LOS and readmission rates across hospitals.

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Fig 2.

Distribution of diagnostic testing across hospitals.

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Fig 3.

Distribution of medications used across hospitals.

In the linear regression analysis for children ≥3 months, the following were associated with increased LOSs: having obtained a chest radiograph, blood culture, or urine culture, and receiving parenteral or oral antibiotics or systemic steroids. Age (in months) was associated with decreased LOS. The results for children who were younger than 3 months are largely similar to those who were≥3 months of age (Table 2).

In the logistic regression analysis in children who were ≥3 months, the following were associated with increased likelihood of antibiotic use: having obtained a chest radiograph, a blood culture, cerebrospinal fluid culture, or urine culture. For younger infants, the same analysis yielded similar results. Use of viral testing was associated with decreased likelihood of antibiotics, although it did not reach statistical significance (OR: 0.91; 95% CI: 0.81 to 1.01). In a separate analysis of all children who were younger than 1 year, the point estimate remained the same and the result was statistically significant (data not shown). Complete results are presented in Table 3.

DISCUSSION

We found significant and wide variation in LOS, readmission rates, treatment approaches, and the use of diagnostic tests for inpatient bronchiolitis. The variation between hospitals remained significant even after controlling for multiple potential confounding factors. To our knowledge, this is the largest study to compare the treatment of infants who are hospitalized for bronchiolitis, and it demonstrates that there is ample room for improvement nationally in the quality of care provided. Decreasing LOS and unnecessary medication and test utilization is also supportive of pediatric patient safety initiatives.

Some of our findings warrant specific comment. Chest radiographs were associated with an increased likelihood of using antibiotics. The findings of bronchiolitis are nonspecific, and the presence of atelectasis, which may not be distinguishable from consolidation, may lead clinicians to treat presumptively even if unnecessarily. Reducing the use of radiographs in children with bronchiolitis does seem warranted and has been shown by others to be associated with decreased probability of antibiotic use.^23,24 Moreover, if virologic testing leads to decreased use of antibiotics, then it might very well be a cost-effective approach. Although a formal cost-effectiveness analysis is beyond the scope of this article, the marginal increased cost associated with such testing likely could be more than offset with the costs of administering antibiotics.

Although the reasons for the variations that we observed in diagnostic and therapeutic approaches are unknown, given that we have endeavored to adjust for a number of potentially explanatory variables including age, comorbidities, etc, one may wonder what accounts for them. One possible explanation is institutional cultural differences (viz, some places “get radiographs,” whereas others “do not”). Radiologic and virologic tests, although costly, are relatively benign. The variation in treatments, however, is more problematic. Data from well-conducted randomized trials have shown that inhaled steroids do not work acutely.^21,22 That a proven ineffective therapy is used in as many as 14% of bronchiolitis patients in some hospitals begs additional study, as does the frequent and wide variation in the use of antibiotics.

There are some limitations to this study that warrant mention. First, our data were collected retrospectively and are cross-sectional. Accordingly, it is not possible to determine whether significant selection bias was present in the use of diagnostic testing, and causal inferences are not appropriate. That is, more severely affected patients may have been more likely to have chest radiographs performed and in fact more likely to have a bacterial superinfection. For example, Wang et al³⁴ found considerable variability in the percentage of children who were admitted with bronchiolitis and had hypoxemia. However, that study included all children who were admitted to the hospital, including those for whom bronchiolitis would not have been the principal diagnosis. It seems highly improbable, however, that variations in the severity of patients alone can account for the wide variations in the use of diagnostic tests, including chest radiographs, especially because our analysis controlled for APR-DRG–derived severity scores, which take into account secondary diagnoses that would be associated with a true need for antibiotic treatment (eg, pneumonia). Second, although we attempted to control for multiple sources of potential confounding in our analyses, it is possible that some residual confounding remains. Whether this systematically biased our results would depend on whether that variation was associated with particular institutions, something that we have no a priori reason to suspect.

Despite these limitations, there are some important implications to our findings. First, there is a need to study the inpatient management of common pediatric conditions. Such widespread variations in the process and outcome measures of care, particularly in situations in which a sound evidence base exists, argues for national quality improvement efforts directed at pediatric inpatient care. Second, better therapeutic approaches are needed for bronchiolitis care. Whether these are at the system level in the form of guidelines or pathways or are in the form of new treatment modalities, robust prospective studies are in order. Ideally, such trials would be accomplished with the collaboration of several institutions, which would make the trials more feasible and the findings more generalizable. For example, it was estimated that a trial of systemic steroids in the treatment of broncholiths would require 728 patients to be powered adequately,⁴ yet smaller, underpowered trials continue to be performed.^35–38 The definitive, large, randomized, controlled trial exceeds the ability of a single institution to conduct but is well within the means of several collaborating hospitals. In the interim, on the basis of the results presented here, individual institutions should direct resources at assessing and potentially improving their inpatient bronchiolitis care.