Total Hip and Knee Arthroplasties Are Highly Cost-Effective Procedures: The Importance of Duration of Follow-Up.

BACKGROUND: Total hip and knee arthroplasties (THA/TKA) are clinically effective but high cost procedures. The aim of this study is to perform a cost-effectiveness analysis of THA and TKA in the New Zealand (NZ) healthcare system. METHODS: Data were collected from 713 patients undergoing THA and 520 patients undergoing TKA at our local public hospital. SF-6D utility values were obtained from participants preoperatively and 1-year postoperatively, and deaths and any revision surgeries from patient records and the New Zealand Joint Registry at minimum 8-year follow-up. A continuous-time state-transition simulation model was used to estimate costs and health gains to 15 years. Quality-adjusted life years (QALYs), treatment costs, and incremental cost-effectiveness ratios (ICERs) were calculated to determine cost effectiveness. ICERs below NZ gross domestic product (GDP; NZ$60 600) and 0.5 times GDP per capita were considered "cost effective" and "highly cost effective" respectively. RESULTS: Cumulative health gains were 2.8 QALYs (THA) and 2.3 QALYs (TKA) over 15 years. Cost effectiveness improved from ICERs of NZ$74,400 (THA) and NZ$93,000 (TKA) at 1 year to NZ$6000 (THA) and NZ$7500 (TKA) at 15 years. THA and TKA were cost effective after 2 years and highly cost effective after 3 years. QALY gains and cost effectiveness were greater in patients with worse preoperative functional status and younger age. CONCLUSION: THA and TKA are highly cost-effective procedures over longer term horizons. Although preoperative status and age were associated with cost effectiveness, both THA and TKA remained cost effective in patients with less severe preoperative scores and older ages.

Risk Factors for Chronic Opioid Use Following Hip and Knee Arthroplasty: Evidence from New Zealand Population Data.

BACKGROUND: Patients awaiting total joint arthroplasty (TJA) have high rates of opioid use, and many continue to use opioid medications long term after surgery. The objective of this study is to estimate the risk factors associated with chronic opioid use after TJA in a comprehensive population-based cohort. METHODS: All patients undergoing TJA in the New Zealand public healthcare system were identified from Ministry of Health records. Dispensing of opioid medications up to 3 years postsurgery and potential risk factors, including demographic, socioeconomic, and surgery-related characteristics, pre-existing medical comorbidities, and use of other analgesic medications prior to surgery, were identified from linked population databases. Logistic regression analysis was used to identify factors associated with chronic postoperative opioid use. RESULTS: The strongest risk factor for chronic postoperative opioid use was preoperative opioid use. Other significant risk factors included perioperative opioid use, history of alcohol or drug abuse, younger age, female gender, knee arthroplasty, several comorbid health conditions, and preoperative use of some analgesic medications. Protective factors included higher education levels and preoperative use of nonsteroidal anti-inflammatory drugs. Most risk factors had similar effects on chronic postoperative opioid use irrespective of the length of follow-up considered (1, 2, or 3 years). CONCLUSION: This study of a comprehensive nationwide population-based cohort of TJA patients with 3 years of follow-up identified several modifiable risk factors and other easily measured patient characteristics associated with higher risk of long-term postoperative opioid use.

The Functional Outcomes of Patients With Knee Osteoarthritis Managed Nonoperatively at the Joint Clinic at 5-Year Follow-Up: Does Surgical Avoidance Mean Success?

BACKGROUND: Nonoperative management of patients with knee osteoarthritis (OA) through multidisciplinary programs may delay or reduce the need for total knee arthroplasty (TKA). However, avoidance of surgery may not represent success for the patient. METHODS: A cohort of 120 patients with knee OA managed with at least 6 months of supervised nonoperative treatment coordinated through the Joint Clinic were reviewed at 5 years. Outcomes including Oxford knee score (OKS), Short Form 12 (SF-12), and SF-6D and other measures including analgesia use, global change, and perception of need for surgery were collected and compared with those from the cohort who had undergone TKA. RESULTS: Seventy (62.5%) surviving patients were still being managed nonoperatively. There was no significant change in any outcome score (OKS, SF-12 physical component score, SF-12 mental component score, SF-6D) (P = .26 to .84). Forty-two patients had undergone TKA with mean time to surgery 29.0 months (range, 9-69 months). In this group, the mean OKS fell from 17.9 at baseline to 10.3 (range, 3-21) preoperatively (P < .0001) and at 5 years there was a significant improvement from baseline in OKS, SF-12 physical component score, and SF-6D scores (P < .0001). All outcome scores and change in scores were significantly higher for the surgical group (all P < .001). CONCLUSION: Although a high proportion of patients with knee OA have avoided surgery at 5 years, their outcomes show no improvement from baseline and are poorer than those who have undergone TKA. Avoidance of surgery should not necessarily be regarded as an indicator of success of nonoperative treatment for the patient.

The Outcomes of Nonoperative Management of Patients With Hip and Knee Osteoarthritis Triaged to a Physiotherapy-Led Clinic at Minimum 5-Year Follow-Up and Factors Associated With Progression to Surgery.

BACKGROUND: The purpose of this study is to determine outcomes of a nonoperative treatment service for hip and knee osteoarthritis (OA), the "Joint Clinic," at minimum 5-year follow-up, and investigate factors that may influence progression to joint replacement surgery. METHODS: This is an observational cohort study of 337 patients with hip (n = 151, 45%) or knee OA (n = 186, 55%) seen at the Joint Clinic, at 5-7 years of follow-up. Kaplan-Meier survival curves were used to determine survivorship of the affected joint and Cox regression used to determine factors associated with time to surgery. RESULTS: At mean 6-year follow up, 188 (56%) patients had undergone or were awaiting total joint arthroplasty, 127 (38%) were still being managed nonoperatively, and 22 (7%) had died without having surgery. Patients with hip OA were more likely to have required surgery (111/151, 74%) than patients with knee OA (77/186, 41%) (chi-square = 33.6, P < .001). The 7-year surgery-free survival for hip OA was 23.7% and knee OA 55.9% (P < .001). Factors associated with increased likelihood of surgery were joint affected (hip, hazard ratio [HR] 2.80), Kellgren-Lawrence (KL) grade (KL 3, HR 2.02; KL 4, 4.79), and Oxford Hip/Knee Score (HR 1.34 for each 5 points worse at baseline). CONCLUSION: More than 50% of the patients referred to secondary care with mild-moderate knee OA may not need surgery at 7 years. Patients with hip OA and those with severe radiographic changes are more likely to require surgery and should not be delayed if there is not an adequate response to conservative measures.