Clinical utility of routine CBC testing in patients with community-acquired pneumonia
The goal of this study was to identify situations in which routine complete blood count (CBC) testing could be avoided in patients with community-acquired pneumonia (CAP). This was a retrospective study of 50 patients with CAP. Vital signs, lab results, assessment and plan data, and computerized provider order entry logs were collected to determine if a lab result or clinical finding changed clinical management. Clinical stability was defined based on Patient Outcomes Research Team study criteria. There were 94 CBCs obtained after admission, of which only 6 were associated with management changes. Only two of these instances involved management changes related to patients’ pneumonia, while the other cases represented chronic illnesses. Among all patients, the positive likelihood ratio of a post-admission CBC predicting a change in clinical management was low (1.12 [95% confidence interval, 0.86-1.44]). Low utility of CBC testing after admission may represent an opportunity to improve the value of care in CAP patients. Journal of Hospital Medicine 2017;12:336-338. © 2017 Society of Hospital Medicine
DISCUSSION
Though small, our initial study suggests the potential opportunity for savings if Choosing Wisely® recommendations for CBC testing were implemented in patients with community-acquired pneumonia.
Our study has several limitations. Note-writing practices and ordering patterns likely varied between providers, and documentation bias may play a role in our results. However, we defined whether a CBC was associated with changes in clinical decision-making or management by incorporating a number of mutually reinforcing elements of the medical record. We recognize, however, that our approach may not capture undocumented clinical issues or other cognitive (eg, reassurance of clinical resolution) reasons why CBCs were obtained.
Even with these limitations, the likelihood of a CBC value meaningfully changing clinical management among patients with CAP appears to be quite low as evidenced by the case descriptions, particularly when obtained in stable patients by PORT criteria and on the day of discharge. Whether clinical stability as measured by PORT score can be used to target patients in whom CBC testing is unnecessary is difficult to discern from our data, as the overall utility of CBCs obtained after admission was quite low and the rate of changes in management was also low. However, even if CBCs are not particularly costly, unnecessary testing may produce harm in the form of prolonged length of stay, making even one unnecessary CBC potentially extremely expensive. More research involving larger-scale studies are needed to determine the “number needed to screen” for the daily CBC in CAP to determine if the cost savings from overtesting and treatment outweigh the potential benefit of a single CBC that changes management.
Disclosure
Nothing to report.
