Bozic (2012) — Patient-related risk factors for periprosthetic joint infection and postoperative mortality following total hip arthroplasty in Medicare patients.

Patient-Related Risk Factors for Periprosthetic Joint Infection and Postoperative Mortality Following Total Hip Arthroplasty in Medicare Patients.

·J Bone Joint Surg Am·2012·496 citations·Hip & Knee

Retrospective cohort study of 40,919 Medicare patients who underwent primary THA between 1998 and 2007. Used multivariate Cox regression with Bonferroni-Holm correction to identify which specific preoperative comorbidities independently predict periprosthetic joint infection and 90-day mortality. Addresses a gap left by composite indices like the Charlson score, which cannot isolate the contribution of individual diseases.

Study Snapshot

Design

Retrospective cohort

Setting: Medicare 5% sample claims database, US

Funding: Mayo Clinic, UCSF, MGH

Objective

Determine whether specific comorbidities increase PJI and mortality risk after total hip arthroplasty

Outcome(s)

Periprosthetic joint infection and 90-day postoperative mortality

Subjects

40,919 Medicare THA patients, 1998–2007

Inclusion

Primary unilateral THA (ICD-9 81.51)
Age ≥65 years
Full 12-month pre-op Medicare enrollment

Exclusion

Age <65 years
HMO enrollment

Follow-up

Up to 10 years (through December 31, 2007)

Statistics

Multivariate Cox regressionWald chi-squareBonferroni-Holm adjustmentAttributable risk estimation

Key Findings

Four comorbidities independently raised PJI risk after full multivariate adjustment — each conferring roughly 36–73% higher relative risk of infection:
–Obesity — HR 1.73
–Rheumatologic disease — HR 1.71
–Coagulopathy — HR 1.58
–Preoperative anemia — HR 1.36
Eight comorbidities independently raised 90-day mortality risk, with hazard ratios spanning a wide range — meaning not all comorbidities carry equal weight in operative candidacy discussions:
–Metastatic cancer — HR 3.14 (highest magnitude)
–Hemiplegia/paraplegia — HR 2.62
–Congestive heart failure — HR 2.11
–Dementia — HR 2.04
–Renal disease — HR 1.98
–Psychosis — HR 1.85
–Cerebrovascular disease — HR 1.40
–Chronic pulmonary disease — HR 1.32
Baseline event rates provide essential context for interpreting these hazard ratios: overall 90-day mortality was 1.98% and PJI-free survival remained 96.65% at seven years — so even a tripling of relative risk still leaves most patients doing well, but the absolute burden matters at population scale.
No single comorbidity explains most events — attributable risks were modest even for the strongest predictors (rheumatologic disease: 5.5% of PJI cases; CHF: 9.9% of 90-day deaths), confirming that multifactorial risk is the rule rather than the exception.
Hypercholesterolemia was paradoxically associated with decreased 90-day mortality (HR 0.62), most likely reflecting health-maintenance bias or systematic under-coding in sicker patients — not a true biological protective effect.

Board PearlFour comorbidities drive PJI risk after THA — rheumatoid disease, obesity, coagulopathy, anemia — and eight drive 90-day mortality, led by metastatic cancer (HR 3.14).

Clinical Relevance

Prior to this study, risk stratification for THA relied on composite scores like the Charlson Comorbidity Index, which collapses all comorbidities into a single number — obscuring which specific diseases actually drive risk.

This paper gives you four concrete targets to optimize before elective THA: correct preoperative anemia, address obesity, manage coagulopathy, and recognize that rheumatologic disease patients carry elevated infection risk regardless of other factors.

For mortality counseling, the numbers that should anchor your consent conversation are CHF (HR 2.11), metastatic cancer (HR 3.14), dementia (HR 2.04), and hemiplegia/paraplegia (HR 2.62). These patients face two to three times the baseline 1.98% 90-day mortality rate.

Do not overlook psychiatric comorbidity: psychosis independently predicts 90-day mortality (HR 1.85), and the authors explicitly call out mental health assessment as a preoperative imperative before elective arthroplasty.

Core

Patient-Related Risk Factors for Periprosthetic Joint Infection and Postoperative Mortality Following Total Hip Arthroplasty in Medicare Patients.

Bozic, Berry, et al.·J Bone Joint Surg Am·2012·496 citations·Hip & Knee

Patient-Related Risk Factors for Periprosthetic Joint Infection and Postoperative Mortality Following Total Hip Arthroplasty in Medicare Patients.

Study Snapshot

Key Findings

Clinical Relevance

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Patient-Related Risk Factors for Periprosthetic Joint Infection and Postoperative Mortality Following Total Hip Arthroplasty in Medicare Patients.

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Key Findings

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Patient-Related Risk Factors for Periprosthetic Joint Infection and Postoperative Mortality Following Total Hip Arthroplasty in Medicare Patients.

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Key Findings

Clinical Relevance

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Patient-Related Risk Factors for Periprosthetic Joint Infection and Postoperative Mortality Following Total Hip Arthroplasty in Medicare Patients.

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Key Findings

Clinical Relevance

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