Background/Purpose: To examine the time-trends in key demographic and clinical characteristics of patients undergoing primary total hip arthroplasty (THA).

Methods: We used the data from the Mayo Clinic Total Joint Registry from 1993-2005 to examine the time-trends in demographics (age, body mass index (BMI)), medical (Deyo-Charlson index) and psychological comorbidity (anxiety, depression) and underlying diagnosis of patients undergoing primary THA.  Chi-square test and analysis for variance were used.  Multivariable-adjusted logistic regression (age, sex, comorbidity-adjusted) compared 1993-95 to other study periods.  Odds ratio (OR) and 95% confidence interval (CI) are presented.

Results: The primary THA cohort consisted of 6,168 patients with 52% women.  Compared to 1993-95, significantly more patients (by >2-times for most) in 2002-05 had: BMI³40, 2.3% vs. 6.3%; depression, 4.1% vs. 9.8%; and anxiety, 3.4% vs. 5.7%; and significantly fewer had an underlying diagnosis of rheumatoid/inflammatory arthritis, 4.2% vs. 1.5% (p²0.01 for all).  In multivariable-adjusted models, compared to 1993-95, significantly more patients in 2003-05 had (all p-values²0.01): BMI³40, OR, 2.79 (95% CI: 1.85, 4.22); Deyo-Charlson Index³3, 1.32 (1.07, 1.63); depression, 2.25 (1.66, 3.05); and anxiety, 1.71 (1.19, 2.15).  Respectively, fewer patients had a diagnosis of RA/inflammatory arthritis: 0.28 (0.17, 0.46; p<0.01).  Over the 13-year study period, Deyo-Charlson index increased by 22% (0.9 to 1.1) and the mean age decreased by 0.7 years (65.0 to 64.3) (p<0.01 for both). 

Conclusion: Obesity, medical/psychological comorbidity and underlying diagnosis changed rapidly in primary THA patients over 13-years.  Studies of THA outcomes and utilization should take these rapidly changing patient characteristics into account.