Patterns of risk of cancer in patients with metal-on-metal hip replacements versus other bearing surface types: a record linkage study between a prospective joint registry and general practice electronic health records in England

• Published in: PloS one 2013-07, Vol.8 (7), p.e65891-e65891
• Main Authors: Lalmohamed, Arief, MacGregor, Alexander J, de Vries, Frank, Leufkens, Hubertus G M, van Staa, Tjeerd P
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Analysis; Arthritis; Arthroplasty, Replacement, Hip - adverse effects; Arthroplasty, Replacement, Hip - statistics & numerical data; Bearing; Biomedical materials; Bone implants; Cancer; Clinical medicine; Confidence intervals; Drugs; Electronic health records; Electronic Health Records - statistics & numerical data; Electronic medical records; England; Epidemiology; Female; Fractures; Gastrointestinal surgery; Health aspects; Health risk assessment; Health risks; Hip; Hip joint; Hip Prosthesis - adverse effects; Hip replacement arthroplasty; Hospitals; Humans; Joint surgery; Male; Medical records; Medical referrals; Medical research; Medicine; Metals; Metals, Heavy - therapeutic use; Middle Aged; Mortality; Neoplasms - etiology; Patients; Pharmaceutical sciences; Pharmacology; Pharmacy; Poisson density functions; Population; Prostheses and implants; Registries; Regression Analysis; Resurfacing; Retrospective Studies; Risk; Risk factors; Selection Bias; Statistical analysis; Studies; Surfacing; Surgeons; Surgical implants; Transplants & implants
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0065891

There are concerns that metal-on-metal hip implants may cause cancer. The objective of this study was to evaluate patterns and timing of risk of cancer in patients with metal-on-metal total hip replacements (THR). In a linkage study between the English National Joint Registry (NJR) and the Clinical Practice Research Datalink (CPRD), we selected all THR surgeries (NJR) between 2003 and 2010 (n = 11,540). THR patients were stratified by type of bearing surface. Patients were followed up for cancer and Poisson regression was used to derive adjusted relative rates (RR). The risk of cancer was similar in patients with hip resurfacing (RR 0.69; 95% Confidence Interval [CI] 0.39-1.22) or other types of bearing surfaces (RR 0.96; 95% CI 0.64-1.43) compared to individuals with stemmed metal-on-metal THR. The pattern of cancer risk over time did not support a detrimental effect of metal hip implants. There was substantial confounding: patients with metal-on-metal THRs used fewer drugs and had less comorbidity. Metal-on-metal THRs were not associated with an increased risk of cancer. There were substantial baseline differences between the different hip implants, indicating possibility of confounding in the comparisons between different types of THR implants.