Variation in Ordering CBCs for Bronchiolitis

Bronchiolitis was the most common primary diagnosis of infants hospitalized in the United States from 2000 to 2001.1 Consequently, much research has focused on the effectiveness of management24 and variation in care, especially the use of unproven diagnostic tests such as chest x‐rays.5 Such variation may have substantial financial and medical impact and has been shown to correlate significantly with hospital costs and length of stay.6

Because bronchiolitis is primarily a clinical diagnosis,7 there is no strong evidence to support the role of diagnostic testing, particularly that of complete blood counts (CBCs).8 Moreover, given the limited diagnostic utility of a single CBC, the benefit of obtaining a second CBC, especially with its associated physical discomfort and additional financial costs, is questionable. Yet despite the lack of evidence and rationale to support initial and repeated ordering of CBCs, we suspect that this practice may be more widespread and variable than currently appreciated.

Using a national database of children's hospitals, we sought to determine the frequency with which CBCs are ordered and repeated during hospitalizations for bronchiolitis, the extent to which these practices vary across institutions, and the relationship of these practices to average charges for a hospital stay.

METHODS

RESULTS

A total of 17,397 children met the inclusion criteria. Children under 3 months were more likely to be covered by Medicaid, be admitted to the ICU, have a longer length of stay, and have at least 1 CBC (Table 1). Of all children hospitalized, 48.2% had at least 1 CBC, and 7.8% had more than 1 CBC performed during their hospital stay. Notably, the proportion of all admissions with at least 1 CBC varied from 23.2% to 79.2% (Fig. 1), and those with repeat CBCs varied from 0% to 18.6% across hospitals (Fig. 2). This variation was significant when stratified by age and adjusted for covariates, which included length of stay and severity of illness (P < .001). In additional post hoc analyses we found differences in ordering pattern by disease severity that should be noted. The proportion of admissions with repeat CBCs varied significantly across severity groups (mild 3.9%, moderate 10.3%, and severe 21.3%, P < .001) and ICU admission status (ICU admission 5.5%, no ICU admission 23%, P <.001). Stratified analyses indicated an interaction between ICU utilization and disease severity, but neither covariate showed significant interactions with other variables in the model (data not shown).

Figure 1

Figure 2

With respect to repeat CBCs, for children at least 3 months old, the strongest predictor was ICU admission (odds ratio [OR] 2.53, 95% CI: 1.69‐3.77), followed by a severe or extreme APR‐DRG severity score (OR 1.75, 95% CI: 1.23‐2.49) and LOS (OR 1.22, 95% CI: 1.15‐1.28). For children less than 3 months old, some of these associations strengthened ICU admission (OR 2.58, 95% CI: 1.84‐3.61), followed by a severe or extreme APR‐DRG severity score (OR 2.31, 95% CI: 1.64‐3.24) and LOS (OR 1.24, 95% CI: 1.16‐1.32). Additional predictors for this age group were a moderate severity score (OR 1.67, 95% CI: 1.29‐2.16) and Medicaid status (OR 1.20, 95% CI: 1.0‐1.43) (Table 2).

Compared with hospitals that had the lowest proportion of admissions in which CBCs were ordered, hospitals with higher proportions of CBCs ordered had significantly higher mean charges per hospital stay (Table 3).

DISCUSSION

We found that in a nationwide sample of children hospitalized with bronchiolitis, 48% had at least 1 CBC and nearly 8% had a repeat CBC ordered during their hospital stay. Moreover, even after adjusting for covariates, the proportion of children with initial and repeat CBCs during a single admission varied widely and significantly across a nationwide sample of children's hospitals.

We can only speculate on the reasons for institutional variation. Although it is not unusual for some cases of illness to vary from a standard course and so trigger initial or repeat evaluations with a CBC, we do not have any a priori reason to expect the proportion of unusual cases to vary by institution in a national cohort of children's hospitals. One compelling explanation for this variation is differing institutional patterns of practice. For example, it may be that some institutions have protocols that require the ordering of a CBC on admission. This practice could prompt a costly and unnecessary testing cascade14 generated by an initially abnormal CBC and so could trigger additional testing and/or procedures, such as x‐rays and parental antibiotics. Such a cascade of testing and intervention could conceivably lead to additional, and dependent, costs not captured by a simple tally of the costs of individual CBCs. Indeed, in our analysis we found that those hospitals with higher proportion of admissions in which CBCs were ordered also had significantly higher admission charges that exceeded the cost of a CBC. Previous studies support the finding that institutional variation in care for viral respiratory illness is significantly correlated with hospital costs.6

Limitations of this study should be noted. First, the PHIS database does not provide indications for, results of, or hospital location of tests, so we cannot determine whether clinical condition or results prompted initial and/or repeat testing. However, because children with complicated courses or atypical disease presentations likely have longer hospital stays, severe disease, or additional diagnoses, we attempted to control for these factors in our analysis. Second, although we selected cases based on a discharge diagnosis of bronchiolitis, it is possible that admitting physicians obtained an initial CBC to rule out alternative diagnoses, such as bacteremia, which can occur but is rare in this population.12, 13 It is plausible that bacteremia is most likely in children with other comorbidities or higher disease severity. In additional stratified analyses we did find that the proportion of repeat CBCs increased with higher disease severity and that there was an interaction between severe disease status and ICU admission. However, all participating institutions are children's hospitals and so are likely to treat children with a range of severity of illness and comorbidities. Finally, as with other analyses of the PHIS database, we used charges to identify diagnostic tests.5

Given that more than 120,000 U.S. infants are hospitalized annually with bronchiolitis,15 the cost and discomfort associated with unnecessary testing warrants attention. The issue of cost is particularly relevant in light of recent research findings of increased costs for admissions at freestanding children's hospitals.16 We found that mean charges per hospital stay were significantly higher for hospitals that had a higher proportion of admissions during which multiple CBCs were ordered. Although we cannot exclude illness severity and age as explanations for the higher charges, we have no reason to believe that one freestanding children's hospital would have a sicker and younger population than another. An alternative and compelling explanation is that a variation in the standard of care exists across these hospitals.

The institutional variation in and the limited evidence for the utility of the ordering of CBCs in the evaluation of bronchiolitis call into question the necessity of this testing strategy. Exploration of the reasons for this institutional variation will help to create quality initiatives and directed interventions to improve and standardize care in bronchiolitis.

Bronchiolitis was the most common primary diagnosis of infants hospitalized in the United States from 2000 to 2001.1 Consequently, much research has focused on the effectiveness of management24 and variation in care, especially the use of unproven diagnostic tests such as chest x‐rays.5 Such variation may have substantial financial and medical impact and has been shown to correlate significantly with hospital costs and length of stay.6

Because bronchiolitis is primarily a clinical diagnosis,7 there is no strong evidence to support the role of diagnostic testing, particularly that of complete blood counts (CBCs).8 Moreover, given the limited diagnostic utility of a single CBC, the benefit of obtaining a second CBC, especially with its associated physical discomfort and additional financial costs, is questionable. Yet despite the lack of evidence and rationale to support initial and repeated ordering of CBCs, we suspect that this practice may be more widespread and variable than currently appreciated.

Using a national database of children's hospitals, we sought to determine the frequency with which CBCs are ordered and repeated during hospitalizations for bronchiolitis, the extent to which these practices vary across institutions, and the relationship of these practices to average charges for a hospital stay.

METHODS

RESULTS

A total of 17,397 children met the inclusion criteria. Children under 3 months were more likely to be covered by Medicaid, be admitted to the ICU, have a longer length of stay, and have at least 1 CBC (Table 1). Of all children hospitalized, 48.2% had at least 1 CBC, and 7.8% had more than 1 CBC performed during their hospital stay. Notably, the proportion of all admissions with at least 1 CBC varied from 23.2% to 79.2% (Fig. 1), and those with repeat CBCs varied from 0% to 18.6% across hospitals (Fig. 2). This variation was significant when stratified by age and adjusted for covariates, which included length of stay and severity of illness (P < .001). In additional post hoc analyses we found differences in ordering pattern by disease severity that should be noted. The proportion of admissions with repeat CBCs varied significantly across severity groups (mild 3.9%, moderate 10.3%, and severe 21.3%, P < .001) and ICU admission status (ICU admission 5.5%, no ICU admission 23%, P <.001). Stratified analyses indicated an interaction between ICU utilization and disease severity, but neither covariate showed significant interactions with other variables in the model (data not shown).

Figure 1

Figure 2

With respect to repeat CBCs, for children at least 3 months old, the strongest predictor was ICU admission (odds ratio [OR] 2.53, 95% CI: 1.69‐3.77), followed by a severe or extreme APR‐DRG severity score (OR 1.75, 95% CI: 1.23‐2.49) and LOS (OR 1.22, 95% CI: 1.15‐1.28). For children less than 3 months old, some of these associations strengthened ICU admission (OR 2.58, 95% CI: 1.84‐3.61), followed by a severe or extreme APR‐DRG severity score (OR 2.31, 95% CI: 1.64‐3.24) and LOS (OR 1.24, 95% CI: 1.16‐1.32). Additional predictors for this age group were a moderate severity score (OR 1.67, 95% CI: 1.29‐2.16) and Medicaid status (OR 1.20, 95% CI: 1.0‐1.43) (Table 2).

Compared with hospitals that had the lowest proportion of admissions in which CBCs were ordered, hospitals with higher proportions of CBCs ordered had significantly higher mean charges per hospital stay (Table 3).

DISCUSSION

We found that in a nationwide sample of children hospitalized with bronchiolitis, 48% had at least 1 CBC and nearly 8% had a repeat CBC ordered during their hospital stay. Moreover, even after adjusting for covariates, the proportion of children with initial and repeat CBCs during a single admission varied widely and significantly across a nationwide sample of children's hospitals.

We can only speculate on the reasons for institutional variation. Although it is not unusual for some cases of illness to vary from a standard course and so trigger initial or repeat evaluations with a CBC, we do not have any a priori reason to expect the proportion of unusual cases to vary by institution in a national cohort of children's hospitals. One compelling explanation for this variation is differing institutional patterns of practice. For example, it may be that some institutions have protocols that require the ordering of a CBC on admission. This practice could prompt a costly and unnecessary testing cascade14 generated by an initially abnormal CBC and so could trigger additional testing and/or procedures, such as x‐rays and parental antibiotics. Such a cascade of testing and intervention could conceivably lead to additional, and dependent, costs not captured by a simple tally of the costs of individual CBCs. Indeed, in our analysis we found that those hospitals with higher proportion of admissions in which CBCs were ordered also had significantly higher admission charges that exceeded the cost of a CBC. Previous studies support the finding that institutional variation in care for viral respiratory illness is significantly correlated with hospital costs.6

Limitations of this study should be noted. First, the PHIS database does not provide indications for, results of, or hospital location of tests, so we cannot determine whether clinical condition or results prompted initial and/or repeat testing. However, because children with complicated courses or atypical disease presentations likely have longer hospital stays, severe disease, or additional diagnoses, we attempted to control for these factors in our analysis. Second, although we selected cases based on a discharge diagnosis of bronchiolitis, it is possible that admitting physicians obtained an initial CBC to rule out alternative diagnoses, such as bacteremia, which can occur but is rare in this population.12, 13 It is plausible that bacteremia is most likely in children with other comorbidities or higher disease severity. In additional stratified analyses we did find that the proportion of repeat CBCs increased with higher disease severity and that there was an interaction between severe disease status and ICU admission. However, all participating institutions are children's hospitals and so are likely to treat children with a range of severity of illness and comorbidities. Finally, as with other analyses of the PHIS database, we used charges to identify diagnostic tests.5

Given that more than 120,000 U.S. infants are hospitalized annually with bronchiolitis,15 the cost and discomfort associated with unnecessary testing warrants attention. The issue of cost is particularly relevant in light of recent research findings of increased costs for admissions at freestanding children's hospitals.16 We found that mean charges per hospital stay were significantly higher for hospitals that had a higher proportion of admissions during which multiple CBCs were ordered. Although we cannot exclude illness severity and age as explanations for the higher charges, we have no reason to believe that one freestanding children's hospital would have a sicker and younger population than another. An alternative and compelling explanation is that a variation in the standard of care exists across these hospitals.

The institutional variation in and the limited evidence for the utility of the ordering of CBCs in the evaluation of bronchiolitis call into question the necessity of this testing strategy. Exploration of the reasons for this institutional variation will help to create quality initiatives and directed interventions to improve and standardize care in bronchiolitis.

Bronchiolitis was the most common primary diagnosis of infants hospitalized in the United States from 2000 to 2001.1 Consequently, much research has focused on the effectiveness of management24 and variation in care, especially the use of unproven diagnostic tests such as chest x‐rays.5 Such variation may have substantial financial and medical impact and has been shown to correlate significantly with hospital costs and length of stay.6

Because bronchiolitis is primarily a clinical diagnosis,7 there is no strong evidence to support the role of diagnostic testing, particularly that of complete blood counts (CBCs).8 Moreover, given the limited diagnostic utility of a single CBC, the benefit of obtaining a second CBC, especially with its associated physical discomfort and additional financial costs, is questionable. Yet despite the lack of evidence and rationale to support initial and repeated ordering of CBCs, we suspect that this practice may be more widespread and variable than currently appreciated.

Using a national database of children's hospitals, we sought to determine the frequency with which CBCs are ordered and repeated during hospitalizations for bronchiolitis, the extent to which these practices vary across institutions, and the relationship of these practices to average charges for a hospital stay.

METHODS

RESULTS

A total of 17,397 children met the inclusion criteria. Children under 3 months were more likely to be covered by Medicaid, be admitted to the ICU, have a longer length of stay, and have at least 1 CBC (Table 1). Of all children hospitalized, 48.2% had at least 1 CBC, and 7.8% had more than 1 CBC performed during their hospital stay. Notably, the proportion of all admissions with at least 1 CBC varied from 23.2% to 79.2% (Fig. 1), and those with repeat CBCs varied from 0% to 18.6% across hospitals (Fig. 2). This variation was significant when stratified by age and adjusted for covariates, which included length of stay and severity of illness (P < .001). In additional post hoc analyses we found differences in ordering pattern by disease severity that should be noted. The proportion of admissions with repeat CBCs varied significantly across severity groups (mild 3.9%, moderate 10.3%, and severe 21.3%, P < .001) and ICU admission status (ICU admission 5.5%, no ICU admission 23%, P <.001). Stratified analyses indicated an interaction between ICU utilization and disease severity, but neither covariate showed significant interactions with other variables in the model (data not shown).

Figure 1

Figure 2

With respect to repeat CBCs, for children at least 3 months old, the strongest predictor was ICU admission (odds ratio [OR] 2.53, 95% CI: 1.69‐3.77), followed by a severe or extreme APR‐DRG severity score (OR 1.75, 95% CI: 1.23‐2.49) and LOS (OR 1.22, 95% CI: 1.15‐1.28). For children less than 3 months old, some of these associations strengthened ICU admission (OR 2.58, 95% CI: 1.84‐3.61), followed by a severe or extreme APR‐DRG severity score (OR 2.31, 95% CI: 1.64‐3.24) and LOS (OR 1.24, 95% CI: 1.16‐1.32). Additional predictors for this age group were a moderate severity score (OR 1.67, 95% CI: 1.29‐2.16) and Medicaid status (OR 1.20, 95% CI: 1.0‐1.43) (Table 2).

Compared with hospitals that had the lowest proportion of admissions in which CBCs were ordered, hospitals with higher proportions of CBCs ordered had significantly higher mean charges per hospital stay (Table 3).

DISCUSSION

We found that in a nationwide sample of children hospitalized with bronchiolitis, 48% had at least 1 CBC and nearly 8% had a repeat CBC ordered during their hospital stay. Moreover, even after adjusting for covariates, the proportion of children with initial and repeat CBCs during a single admission varied widely and significantly across a nationwide sample of children's hospitals.

We can only speculate on the reasons for institutional variation. Although it is not unusual for some cases of illness to vary from a standard course and so trigger initial or repeat evaluations with a CBC, we do not have any a priori reason to expect the proportion of unusual cases to vary by institution in a national cohort of children's hospitals. One compelling explanation for this variation is differing institutional patterns of practice. For example, it may be that some institutions have protocols that require the ordering of a CBC on admission. This practice could prompt a costly and unnecessary testing cascade14 generated by an initially abnormal CBC and so could trigger additional testing and/or procedures, such as x‐rays and parental antibiotics. Such a cascade of testing and intervention could conceivably lead to additional, and dependent, costs not captured by a simple tally of the costs of individual CBCs. Indeed, in our analysis we found that those hospitals with higher proportion of admissions in which CBCs were ordered also had significantly higher admission charges that exceeded the cost of a CBC. Previous studies support the finding that institutional variation in care for viral respiratory illness is significantly correlated with hospital costs.6

Limitations of this study should be noted. First, the PHIS database does not provide indications for, results of, or hospital location of tests, so we cannot determine whether clinical condition or results prompted initial and/or repeat testing. However, because children with complicated courses or atypical disease presentations likely have longer hospital stays, severe disease, or additional diagnoses, we attempted to control for these factors in our analysis. Second, although we selected cases based on a discharge diagnosis of bronchiolitis, it is possible that admitting physicians obtained an initial CBC to rule out alternative diagnoses, such as bacteremia, which can occur but is rare in this population.12, 13 It is plausible that bacteremia is most likely in children with other comorbidities or higher disease severity. In additional stratified analyses we did find that the proportion of repeat CBCs increased with higher disease severity and that there was an interaction between severe disease status and ICU admission. However, all participating institutions are children's hospitals and so are likely to treat children with a range of severity of illness and comorbidities. Finally, as with other analyses of the PHIS database, we used charges to identify diagnostic tests.5

Given that more than 120,000 U.S. infants are hospitalized annually with bronchiolitis,15 the cost and discomfort associated with unnecessary testing warrants attention. The issue of cost is particularly relevant in light of recent research findings of increased costs for admissions at freestanding children's hospitals.16 We found that mean charges per hospital stay were significantly higher for hospitals that had a higher proportion of admissions during which multiple CBCs were ordered. Although we cannot exclude illness severity and age as explanations for the higher charges, we have no reason to believe that one freestanding children's hospital would have a sicker and younger population than another. An alternative and compelling explanation is that a variation in the standard of care exists across these hospitals.

The institutional variation in and the limited evidence for the utility of the ordering of CBCs in the evaluation of bronchiolitis call into question the necessity of this testing strategy. Exploration of the reasons for this institutional variation will help to create quality initiatives and directed interventions to improve and standardize care in bronchiolitis.