Cost-effectiveness of surgical interventions for the management of osteoarthritis: a systematic review of the literature

Electronic databases (Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations and Ovid MEDLINE(R), Ovid EMBASE Classic and EMBASE, EBM Reviews-Cochrane Database of Systematic Review, EBM Reviews-NHS Economic Evaluation Database, PubMed, INAHTA database and HTA websites) were searched for economic evaluations associated with any clinical trials or cohort-based trials that assessed all types of treatment modalities (pharmacological, non-pharmacological, surgical) for all types of OA.

Additional literature which was considered as potentially relevant was identified from the bibliographies of the retrieved articles and search engines such as Google Scholar. Any studies with limited access were retrieved by emailing the author(s) and no language restrictions were imposed. The searches were conducted between 2004 and 2016. This timeframe was chosen for pragmatic reasons and in order to capture the most recent studies. The detailed search terms that were used, has been outlined in Additional file 1.

All titles and abstracts of retrieved articles were screened and any duplicates were excluded from the initial list. Each article was then checked for suitability in terms of their potential in assessing the cost-effectiveness and economic analysis of various treatment modalities for management of OA. Full text articles of these selected titles were retrieved and reviewed for further selection in accordance to pre-specified inclusion and exclusion criteria. The selection of articles was carried out independently by two reviewers [HK] and [RO]. Results from each reviewer were compared and any differences were resolved through consultation among reviewers.

It was from this broad pool of papers that the following, more specific, inclusion and exclusion criteria were applied, in order to identify studies falling within the scope of this paper.

The inclusion criteria for this systematic review were divided into 5 main components as follows:

The exclusion criteria for this review were as follows:

The following data was extracted from the selected studies: Study characteristics such as type of economic analysis, population, interventions, comparators, perspective, time horizon, and types of modelling used, effectiveness and cost measures, main results, ICER, base-case outcomes and sensitivity analyses being used. A summary of the studies relating to surgical interventions for the treatment of hip and knee OA is presented in Table 1.

Assessment of the quality of included studies was performed by using the Consolidated Health Economic Evaluation Reporting Standards or CHEERS [15] (Additional file 1) and Philips criteria checklist [16] (Additional file 1) for model based studies. All included studies were also quantitatively assessed using the Quality of Health Economic Studies (QHES) instrument (Additional file 1) which was designed to evaluate the appropriateness of the methodology, the validity and transparency of the study results and the comprehensiveness of reporting the study itself [17].

The initial (broad) search yielded 303 potentially relevant articles and after reviewing the abstracts and applying the inclusion criteria, 121 studies were initially included for full text review. After applying exclusion criteria set out above, a total of 98 articles were excluded, mainly because they were duplicates (6 studies), were not concerned with assessing surgical interventions (38 studies), not limited to knee and hip OA patients (19 studies), not full economic evaluations (22 studies), protocols (3 studies) and systematic reviews (10 studies). A total of 23 studies were included in the final sample for this paper (Fig. 1).

All studies included in this review were published between 2004 and 2016 and were conducted across nine different countries (USA, Italy, Canada, Australia, Finland, UK, Singapore, Belgium and Romania). The types of economic evaluations conducted were mainly cost-utility analysis (78%) and cost-effectiveness analysis (13%) with one study conducting a cost-benefit analysis [18] and another conducting both a cost-utility analysis and a cost-effectiveness analysis [19]. Sixteen studies were model based, whilst six were trial based (Table 1). Most studies adopted either a healthcare (nine studies) or a societal perspective (eight studies). Two studies however adopted both a healthcare and a societal perspective [19, 20]. Of the remaining studies, four did not specifically mention the perspective that was adopted [21‐24].

Three studies only incorporated direct medical costs in their analysis even though they stated that they adopted a societal perspective [25‐27]. Most studies described the comparators that were used; one study stated that the comparator of choice was a non-operative strategy [28] but did not give any specific details about the non-operative strategy used. For studies that used the QALY as an outcome measure, various health-related quality of life (HR-QoL) instruments such as the SF-36, EQ-5D, SF-6D, 15-Dimensional Utility Index (15D), Health Utility Index (HUI) and Health Assessment Questionnaire (HAQ) were used. Two studies [25, 29], however, did not specifically mention the tools that were used to derive the QALY estimates. Apart from the generic HR-QoL instruments, some studies utilised disease-specific health state instruments. For instance, Räsänen et al [28] used Harris Hip Score (HHS) and Knee Society Score (KSS) as complementary disease-specific tools for the 15D generic instrument used in the study. Other disease-specific tools used were Oxford Hip Score (OHS), Oxford Knee Score (OKS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The most widely used tool by healthcare providers in assessing OA patients is WOMAC Osteoarthritis Index which consists of 24 items used to evaluate pain, stiffness and physical functions of OA patients in daily living [30].

For surgical modalities for knee OA, the most common intervention was total knee arthroplasty whilst the most common surgical modality for hip OA was total hip arthroplasty.

One study compared THA to a non-operative strategy from a health care perspective and found THA to be a cost-effective intervention [28]. Another study compared the intervention to a do nothing approach over patients’ lifetime in the Australian population from a health system perspective and found THA to be cost-effective [35]. The study by Mota used a Markov modelling approach to compare early and delayed hip arthroplasty in a cohort of patients based on sex and age (50-59 years, 60-74 years and 75 years and over) from a health provider perspective and the results from this study suggest that early THA is a cost-effective option across groups based on age and sex [38].

Four studies compared various techniques for THA. The first study [39] compared two techniques for THA (cementless and hybrid) over patients lifetime using a Markov model and found the cementless technique to be cost-effective compared to the hybrid technique in most cases. However, the cementless technique was found to be dominant in patients less than 43 years whilst the hybrid technique seemed to be dominant in patients aged 83 and over.

The second study assessed the lifetime cost-effectiveness of cemented, cementless and hybrid techniques and found the hybrid to be the most cost-effective compared to cemented and cementless in 60, 70 and 80 year old patients. The results obtained in this study were similar for both men and women [23]. The third study [40] compared five different techniques for THA from an NHS/PSS perspective and concluded that it is difficult to make a choice between techniques based on cost-effectiveness grounds alone. The fourth study assessed the cost-effectiveness of three types of prosthesis for hip replacement (cemented, cementless and hybrid) in adults aged between 55 and 84 years. The study found the hybrid prosthesis to be the most cost-effective across all age groups, with the exception of 80 year old women where the cemented prosthesis was the most cost-effective [41].

For studies that considered implant systems, one study evaluated the KineSpring implant system and found it to be cost-effective compared to other surgical and conservative treatments [22]. Another study compared arthroscopic surgery with a non-operative treatment and found that arthroscopic surgery was not a cost-effective option [19]. A summary of the results and conclusions of studies assessing the cost-effectiveness of surgical interventions is presented in Table 2.

Based on the Quality of Health Economic Studies (QHES) instrument, a total of six studies were categorised as good quality with scores of 75 and above whilst fourteen other studies were categorised as moderate quality with scores between 50 to 74 (Table 2 and Additional file 1). Three studies had scores below 50 [21, 22, 28] and a close examination of these studies revealed striking flaws such as not reporting the source of transition probabilities, perspectives, discount rate, cycle length and time horizon. One study [22] did not perform any sensitivity analysis to deal with the sampling uncertainty or give any details of the source of effectiveness data.

Fourteen out of the eighteen model based studies used Markov/semi-Markov models due to the chronic nature of OA and the ability of such models to handle recurrent events. Other model types that were used include decision tree modelling [25] and discrete-event simulation (DES) which has the flexibility to accommodate a richer structure without making it unmanageable in size [35]. Only one study did not specify which model type was used as the basis of its economic evaluation [22]. The time horizon used in the model based studies varied from one year to lifetime and most of the studies chose a 1-year cycle length for transitions to occur from one health state to another. For those studies that accounted for revision of surgery and failure of implant as one of the outcomes, one year is considered as a reasonable time to decide for further management, should any of the events occur. The most commonly used sensitivity analysis in the model-based economic evaluations in this review is probabilistic sensitivity analysis. This involves specifying distributions for model parameters to represent uncertainty in their estimation followed by employing Monte Carlo simulation to select values at random from those distributions [42]. Other types of sensitivity analysis used were deterministic, one-way and two-way sensitivity analysis, subgroup analysis, regression analysis and scenario analysis.

To the best of our knowledge, this is the only systematic review pertaining to the cost-effectiveness of surgical treatment modalities in management of osteoarthritis. In addition, methodological issues related with economic evaluations of surgical interventions in management of OA were also assessed and reported in this study. This study critically assessed the quality of included studies both qualitatively with the Philips and CHEERS checklists as well as quantitatively using the QHES scoring tool.

Because a broader search strategy was initially adopted, a large number of studies were hand searched. This may mean that we have been able to identify a larger number of relevant papers than if the initial search criteria had been limited to surgical interventions for hip and knee OA.

Limitations of the study include the following: Due to the study aims and the need to include as many studies as possible, we did not exclude any studies based on the results of the quality checks. Hence, the robustness of this systematic review may possibly be affected by the poor quality studies included in this report. In addition to this, the quality assessment was carried out by one reviewer. Second, studies that were included in this review were conducted across nine countries which may lead to problems such as generalisability and transferability of the study findings to other settings due to differences in factors such as clinical practice, prices and epidemiology of disease [47, 48]. In addition to this, guidance in many countries does not consider economic data to be transferable to their settings in most cases [49, 50]. As a result, care must be taken when interpreting the results of this study in a particular context.

Clinical guidelines by the National Institute for Health and Care Excellence in the UK recommend a holistic approach to osteoarthritis assessment and management [8]. The guidelines advocate for patient education and self-management to enhance understanding of the condition and its management. Unfortunately, the information on economic analyses in the guidelines is confined to pharmacological and conventional treatments. Cost-effectiveness findings related to surgical interventions were merely focused on time to referral for surgery as being highlighted in the guidelines by National Collaborating Centre for Chronic Conditions [51]. It is therefore recommended that guidelines should also include suggestions for the use of surgical interventions as well as other forms of treatments and management techniques. One of the concerns around surgical interventions such as arthroplasty relates to the cost implications surrounding it. It may be argued that avoiding or delaying these surgical procedures may have a positive impact on health budgets through savings. However, it should be noted that delaying such a procedure may have a detrimental effect on the quality of life of patients and may lead to additional costs down the line. Studies included in this review concluded that delaying arthroplasty (both knee and hip) was not a cost-effective option and that the health related quality of life lost as a result of the delay is greater than the savings in costs that may occur from delaying the procedure [38]. It is therefore suggested that future cost-effectiveness studies assess the cost-effectiveness of delaying surgery in various sub-groups of patients and in various settings in order to reach a consensus about when the operation should be conducted and when delaying surgery would yield the optimum results.

Although interventions such as THA have been shown to be cost-effective, there needs to be additional studies comparing the various types of THA surgeries in order to maximise benefits from the available resources. In addition, other interventions such as MoM-HRA have been shown to be cost-effective in younger patients [37]. Therefore health policy makers should take such evidence into consideration when providing guidance. Policy makers and stakeholders should therefore consider TKA and THA as opposed to non-operative/non surgical strategies particularly for patients with severe/advanced stage OA [18]. From this review, it is clear that there is limited evidence with respect to other forms of surgical treatments. It is therefore suggested that additional studies should be conducted in order to determine the cost-effectiveness of other forms of surgical interventions for both knee and hip OA.

This study found that approximately 36% percent of studies limited their analysis to a healthcare perspective. It should however be noted that a large proportion of the economic burden of OA is related to indirect costs and productivity losses [6]. Thus, the societal perspective has the potential to capture all important impacts on the whole society. Recent guidelines suggest that due to the chronic nature of OA, a broader societal perspective is preferred [9, 52]. It should however be recognised that national guidelines such as those in the UK recommend that economic analysis should be undertaken from a health service perspective [53] and as a result, analysts in countries like the UK might limit their study to the health service perspective. However, it is suggested that all studies should also consider the societal perspective within sensitivity analysis in order to provide a better picture of the true burden associated with OA and also ensure that the results are more generalisable to other settings.