Mahomed (2003) — Rates and outcomes of primary and revision total hip replacement in the united states medicare population

Rates and Outcomes of Primary and Revision Total Hip Replacement in the United States Medicare Population

Mahomed, Baron·J Bone Joint Surg Am·2003·798 citations·Hip & Knee

This population-based study used Medicare claims from July 1995 to June 1996 to characterize the rates and ninety-day outcomes of primary and revision THA in patients 65 and older. It was the first study to report the epidemiology of revision THA. The cohort included 61,568 primary and 13,483 revision patients, with fracture cases excluded from the primary group.

Study Snapshot

Design

Retrospective population cohort

Setting: US Medicare population, 1995-1996

Funding: NIH, AHRQ, foundations

Objective

Whether rates and ninety-day outcomes of primary and revision THA differ by patient demographics in the Medicare population

Outcome(s)

Incidence rates and five ninety-day complications

Subjects

75,051 patients

61
568Primary
13
483Revision

Inclusion

Age 65 and older
Elective primary or revision THA
US resident, both Medicare parts

Exclusion

Hip infection, cancer, or fracture (primary)
HMO enrollment
Conversion of prior hip surgery

Follow-up

90 days postoperative

Statistics

Poisson regressionGeneralized estimating equationsLogistic regressionStandardized mortality ratio

Key Findings

Primary THA was performed three to six times more often than revision THA. Primary rates ranged 13.9 to 29.9 per 10,000, revision rates 3.4 to 6.4 per 10,000. Rates rose with age until 75-79 years, then declined.
Ninety-day complications after primary THA:
–Mortality: 1.0%
–Pulmonary embolus: 0.9%
–Wound infection: 0.2%
–Readmission: 4.6%
–Dislocation: 3.1%
Ninety-day complications after revision THA were roughly double for most outcomes:
–Mortality: 2.6%
–Pulmonary embolus: 0.79%
–Wound infection: 0.95%
–Readmission: 10.0%
–Dislocation: 8.4%
Ninety-day mortality after primary THA matched the age-matched Medicare population (SMR 0.9), but revision nearly doubled it (SMR 1.9). Use this to counsel that primary THA does not raise short-term mortality, while revision carries real added risk.
Blacks underwent THA at significantly lower rates than whites even after adjusting for comorbidity and income (primary rate ratio 0.59, revision 0.63). The gap is not explained by osteoarthritis prevalence, pointing to a true disparity in access.
Advanced age was the strongest predictor of death, with odds 5.8x higher for ages 85-89 versus 65-69 after primary THA and 6.4x after revision. Medical comorbidity and low income also raised the odds of death, wound infection, and readmission.
Pulmonary embolism risk did not differ between primary and revision replacement, and was the one 90-day outcome not associated with increasing age — which the authors suggest may reflect the widespread use of DVT prophylaxis in both procedures.

Board PearlRevision THA roughly doubles the ninety-day risk of death, readmission, dislocation, and infection compared with primary THA.

Clinical Relevance

When counseling an elderly patient about revision THA, quote roughly double the ninety-day risk of death, readmission, dislocation, and infection compared with a primary. This is concrete data you can use in the clinic.

Primary THA does not raise ninety-day mortality above the age-matched baseline (SMR 0.9), so reassure a medically fit older patient that the operation itself is safe. Revision is different, with an SMR of 1.9. Risk-stratify preoperatively using the factors this paper identified: advanced age, male sex, medical comorbidity, and low income all raise the odds of adverse outcomes.

The racial disparity finding is board-relevant and durable. Blacks underwent THA at significantly lower rates than whites even after controlling for comorbidity and income, and this is not explained by any difference in osteoarthritis prevalence.

Core

Rates and Outcomes of Primary and Revision Total Hip Replacement in the United States Medicare Population

Mahomed·J Bone Joint Surg Am·2003·798 citations·Hip & Knee

Rates and Outcomes of Primary and Revision Total Hip Replacement in the United States Medicare Population

Study Snapshot

Key Findings

Clinical Relevance

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Rates and Outcomes of Primary and Revision Total Hip Replacement in the United States Medicare Population

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Rates and Outcomes of Primary and Revision Total Hip Replacement in the United States Medicare Population

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Rates and Outcomes of Primary and Revision Total Hip Replacement in the United States Medicare Population

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