THR improves patient survival rates up to six years

Medicare patients not treated with THR more commonly are hospitalized for 12 of the 16 diagnoses included in the Charlson comorbidity index.

Patients who receive elective primary total hip replacement have better survival rates up to six years postop than patients who do not undergo surgery, a controlled study confirms.

Jane Barrett, MSc, a research assistant professor of community and family medicine at Dartmouth Medical School (DMS) in Lebanon, N.H., conducted the study with colleagues at DMS and at Brigham and Women’s Hospital in Boston. The researchers compared the six year survival rates between Medicare patients who did and did not undergo total hip replacement (THR). All data were gathered from Medicare claims records, according to the study.

“We found that the [THR] cohort had less major comorbidity than did the matched controls, with an approximately 30% lower prevalence for most serious diseases ...,” the authors said in the study.

“Our observations confirm and extend the observations made in Scandinavian studies and in the earlier American studies that patients who have had a primary [THR] have a better survival rate ... after the perioperative period,” they said.

The researchers published their results in the American edition of The Journal of Bone and Joint Surgery.

Medicare recipients

Barrett and colleagues reviewed Medicare claims data for 28,469 patients who underwent primary THR from January through June 1996. To be included, all THR patients had to have an ICD-9-CM procedure code of 81.51 and a surgeon's CPT code of 27130.

The researchers excluded patients treated for hip, femur or other fractures, patients not enrolled in both Medicare Part A and Part B, patients who were not residents of the U.S., and patients older than 99 years.

The control group included 142,345 randomly selected Medicare patients frequency-matched to the THR group in a 5-to-1 ratio. Both groups had a mean baseline age of 74.8 ? 5.8 years.

To adjust for comorbidities, the researchers also reviewed discharge diagnoses on Medicare hospital claims files to determine whether each of 16 serious diagnoses, included in the Charlson comorbidity index, had been made within one year before the baseline date. Similar numbers of patients in both groups had been hospitalized during the prior year for such diagnoses — 3490 THR patients (12.3%) and 17,944 control patients (12.6%), according to the study.

“Nevertheless, there was clear evidence that the control beneficiaries had worse health than the [THR] recipients,” the study authors said. Control patients were much more likely to have had multiple diagnoses and “substantially” more likely to have 12 of the 16 serious diagnoses, they noted.

Of the 16 serious diagnoses, THR patients more commonly had only peptic ulcers and rheumatic disease, they said.

Lower mortality

THR patients had higher mortality rates during the three months immediately following surgery. However, by 90 days the survival curves had crossed, with about 1% of patients in each group having died. THR patients then began showing “considerably better” survival, with 16% having died at five years compared with 22% of control patients, according to the study.

But by the sixth year, just over 3% of patients in each group had died, “showing that very little of the advantage of the [THR] patients remained,” the authors said.

After six years, THR patients had a 79% survival probability vs. a 72% survival probability for control patients.

The authors speculated that the better survival rates among THR patients could be due to the surgery, although unmeasured differences between the groups, such as smoking and body mass index, may also be involved.

“After the procedure, use of [NSAIDs] and narcotic pain medications typically decreases and patients are able to exercise again — factors that could improve their health,” the authors said.

For more information:
Barrett J, Losina E, Baron JA, et al. Survival following total hip replacement. J Bone Joint Surg Am. 2005;87-A:1965-1971.