AIM: Attention to multiple CABG quality metrics reduces costs, boosts quality

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Focusing on improving quality process measures overall, rather than individually, can improve patient care after CAGB surgery, while at the same time decreasing length of stay and costs, according to a study published in the July 26 edition of the Archives of Internal Medicine.

Andrew D. Auerbach, MD, of the University of California, San Francisco, and colleagues studied the relationship between surgeon and hospital volume, length of stay and costs by evaluating 81,289 patients who underwent CABG procedures between Oct. 1, 2003, and Sept. 1, 2005. They analyzed patients treated by 1,451 physicians at 164 hospital sites and who were part of the Perspective database that measured quality and healthcare utilization.

Patients had a mean age of 65 years and 72 percent were men. Additionally, 72 percent of patients had hypertension, 31 percent had diabetes and 23 percent had obstructive pulmonary disease.

The majority of hospitals and physicians in the study were lowest volume providers, 51 percent and 78 percent, respectively. Researchers estimated that the average cost of one CABG procedure was $25,140 and length of stay was seven days.

The researchers used mutlivariable models to assess, first, the association between hospital and physician volume and individual quality measures as single predictors in individual models for each predictor. Secondly, in order to determine how volume and missed quality procedures were associated, the researchers used models that included volume and indiviaual quality measures.

These quality measurements included: antimicrobial use/discontinuation to prevent surgical site infection, serial compression device use to prevent venous thromboembolism, and administration of beta-blockers or lipid-lowering statins post-procedure.

They found that 77 percent of patients were not delivered compression devices, and 22 percent of patients did not receive beta-blockers within two days of CABG. Only 12 percent of patients did not experience a missed quality measure and 44 percent of patients missed three or more quality measures.

Administration of antimicrobial prophylaxis resulted in a longer length of stay, but not costs, while administering antimicrobials in the first 48 hours after CABG and not delivering a compression device to prevent thromboembolism was associated with longer length of stay.

Auerbach et al split physician volume and hospital volume into quartiles. Hospital volume ranged from 112 procedures per year in the lowest volume quartile to 664 for the highest volume quartile. Physician volume for these procedures ranged from 12 per year to 155 per year.

As volume rose, so did the number of patients who missed one or more quality measures.

Researchers found that lowest volume hospitals had substantially higher costs but similar length of stay compared to other hospitals. According to the research, volume was not associated with length of stay in the models that adjusted for clinical factors alone or clinical factors and quality measurements.

"The addition of volume as another adjuster in our models did not appreciably alter the adjusted associations between individual quality measures and length of stay or costs, suggesting that the associations between volume and resource use and between quality and resource use were independent of each other," the authors wrote.

Researchers found the associations between hospital and physician volume and costs and length of stay to be identical whether  the researchers adjusted for overall care quality or individual quality measures. According to the researchers, this suggested an independence of the association between the overall quality and volume measures' associations with length of stay or costs.

In a secondary analysis, the researchers found a statistically significant interaction between hospital volume, quality, length of stay and costs, "suggesting small incremental benefits of having higher quality care at a higher-volume hospital or from a busier surgeon," the authors wrote.

The researchers found that the lowest volume hospitals had the highest cost, but similar length of stays at higher volume hospitals; however researchers said, "In contrast, missing one or more quality measure was strongly associated with higher costs and longer length of stay, which was essentially independent of the volume of the surgeon or hospital.

"These findings suggest that efficiency can be improved in CABG by advising patients to avoid low-volume healthcare providers, while encouraging investment in improving the reliability of hospital care.”

If patients avoided these low-volume centers, costs have the potential to be reduced by 16 percent, the researchers said. And they estimated that if patients living near a lower-volume center instead visited a hospital with a higher-volume, no matter the quartile, an annual cost savings between $85 million and $171 million could be seen.

"Our results more often suggest that promotion of adherence to process measures is a separate approach for improving care efficiency in cardiac surgery, but maximizing overall rather than individual measure performance is critical," the authors wrote. "While worse performance on individual measures in our study was inconsistently associated with costs or length of stay and had a minimal impact on the association between volume and outcomes, the number of care processes missed was a strong and consistent predictor of longer length of stay and costs."

Additionally, they urged that healthcare reform efforts focus more closely on improving care by assessing whether incentivizing providers for their quality improvement efforts would be beneficial.

In an accompanying editorial, David L. Brown, MD, of the SUNY-Stony Brook School of Medicine, wrote, “The association between procedural volume and short-term mortality has been repeatedly demonstrated for CABG surgery.

“However, the strength of the association between volume and quality is inconsistent and dependent on many factors including the type of data used (clinical vs. administrative), the method of risk adjustment (none vs. hierarchical vs. logistic regression), the age of the patient population, and the location of the population (California vs. New York), to name just a few.”

Brown offered that other outcome measures, besides mortality, should be publicly reported and said that at the patient level quality is “all about outcomes.” Outcomes, he said, “should be measured beyond the in-hospital or immediate post-discharge period, should be risk adjusted and should be weighted according to relevance to patients and integrated into a global quality score.

“After more than 40 years of performance of CABG surgery, it is time to put the patient at the center of discussion, planning and research about clinical outcomes and quality."

Brown offered that such a change would have modest costs, but great reward.