Medicare started doing something differently in October 2012, as part of the new health care law. It began tethering some of hospitals’ payments to patient satisfaction rankings.

All of the sudden, hospitals could get bonuses if their patients gave them a positive review; clean rooms and attentive nurses became relevant to providers’ bottom lines. Hospitals began making big investments in making their patients happier.

While that might improve patient rankings, a new study suggests it will not improve quality of care: There is little relationship between patient satisfaction and the quality of care they receive.

A team of Johns Hopkins University researchers looked at how 31 large hospitals scored on patient satisfaction and compared that to how well these same institutions scored on safety measures. These included measures such as whether a catheter was removed within two days of surgery or a prophylactic antibiotic was delivered one hour prior to the procedure.

When researchers compared these two sets of measures, they found that high scores on patient satisfaction was “not associated with hospital compliance with process-of-care measures.” Hospitals could do well on pleasing patients, but that had nothing to do with how well their doctors and nurses did on safety metrics.

“We applaud the introduction of patient satisfaction as a metric of health care, recognizing that satisfaction measures the important customer service component of a patient’s experience,” the authors write in JAMA Surgery. “However, the use of patient satisfaction as a comprehensive measure of quality to determine hospital reimbursement must be questioned in the absence of other reliable outcome metrics.”

This is not the first research to find little relationship between patient satisfaction and quality outcomes. Some studies have hinted at an inverse relationship, where patients who rated their doctors as the best at communication actually had the least realistic expectations for their care.

This growing body of research questions whether patient satisfaction ought to be a metric that hospitals get paid for. Is there still value to patients’ rating their hospital trip highly, even if it doesn’t necessarily reflect better care.

These authors suggest it's not. “We caution the use of patient satisfaction as a large component of hospital reimbursement formulas before its contribution to the determination of quality in surgery is better understood,” they write. “At present, little evidence supports its ability to predict the quality of surgical care.”