Treatment costs to prevent or treat upper gastrointestinal adverse events associated with NSAIDs

Selective versus non-selective NSAIDs as prophylaxis for heterotopic ossification following hip arthroplasty: a meta-analysis

Background

Some patients have demonstrated evidence of heterotopic ossification (HO) following total hip arthroplasty (THA). Selective and non-selective non-steroidal anti-inflammatory drugs (NSAIDs) are used as prophylaxis for HO following THA. This meta-analysis compared selective versus non-selective NSAIDs as prophylaxis for HO following THA.

Material and methods

The present study was conducted according to the PRISMA 2020 guidelines. All the clinical investigations comparing selective versus non-selective NSAIDs as prophylaxis for HO following THA were accessed in February 2022. An assessment of the methodological quality and statistical analyses were performed through the risk of bias summary tool of the Review Manager 5.3 software (Cochrane Collaboration, Copenhagen). The modified Brooker staging system was used to rate the efficacies of the interventions.

Results

Data from 8 studies and 1526 patients were collected. 60.8% were female. No difference was found in the sample size, mean age, and percentage of females between the two groups at baseline. No statistically significant difference was found between selective and non-selective NSAIDs in term of efficacy. 72% (1078 of 1502) of the patients were classified as Brooker 0, 21% (322 of 1502) as Brooker I, 5% (80 of 1502) as Brooker II, 1% (16 of 1502) as Brooker III, and 0.1% (2 of 1502) as Brooker IV.

Conclusion

Selective and non-selective NSAIDs were equally effective when used as prophylaxis for HO following THA.

Level of evidence

Level III, systematic review and meta-analysis.

In search of safe pain relief: The analgesic and anti-inflammatory activity of phytosteryl ibuprofenates

β-Sitosteryl (S)-ibuprofenate (2), stigmasteryl (S)-ibuprofenate (3), ergosteryl (S)-ibuprofenate (4), and cholesteryl (S)-ibuprofenate (5) were prepared in 70-75% yields by Steglich esterification and were characterized by 1D and 2D NMR, as well as by MS. The new esters were evaluated in in vivo pain models of antinociception and anti-inflammation using the writhing, formalin, and carrageenan tests, in mice and rats, and the results were compared with those of (S)-ibuprofen (1). Damage to the gastric mucosa of animals was also assessed. The results indicated that 2-5 have comparable or eventually better activity than 1 at the same mg/kg doses. Since the molecular weight ratio of esters 2-5 to ibuprofen is about 3-1, the amount of truly incorporated ibuprofen was roughly one third to achieve similar effects. This resulted in minimal gastrointestinal damage in the stomach of the animals, in contrast to the large gastric injury caused by (S)-ibuprofen.

Risk of acute myocardial infarction during use of individual NSAIDs: A nested case-control study from the SOS project

BACKGROUND

Use of selective COX-2 non-steroidal anti-inflammatory drugs (NSAIDs) (coxibs) has been associated with an increased risk of acute myocardial infarction (AMI). However, the risk of AMI has only been studied for very few NSAIDs that are frequently used.

OBJECTIVES

To estimate the risk of AMI for individual NSAIDs.

METHODS

A nested case-control study was performed from a cohort of new NSAID users ≥18 years (1999-2011) matching cases to a maximum of 100 controls on database, sex, age, and calendar time. Data were retrieved from six healthcare databases. Adjusted odds ratios (ORs) of current use of individual NSAIDs compared to past use were estimated per database. Pooling was done by two-stage pooling using a random effects model (ORmeta) and by one-stage pooling (ORpool).

RESULTS

Among 8.5 million new NSAID users, 79,553 AMI cases were identified. The risk was elevated for current use of ketorolac (ORmeta 2.06;95%CI 1.83-2.32, ORpool 1.80; 1.49-2.18) followed, in descending order of point estimate, by indometacin, etoricoxib, rofecoxib, diclofenac, fixed combination of diclofenac with misoprostol, piroxicam, ibuprofen, naproxen, celecoxib, meloxicam, nimesulide and ketoprofen (ORmeta 1.12; 1.03-1.22, ORpool 1.00;0.86-1.16). Higher doses showed higher risk estimates than lower doses.

CONCLUSIONS

The relative risk estimates of AMI differed slightly between 28 individual NSAIDs. The relative risk was highest for ketorolac and was correlated with COX-2 potency, but not restricted to coxibs.

The efficacy of celecoxib in preventing heterotopic ossification recurrence after open arthrolysis for post-traumatic elbow stiffness in adults

BACKGROUND

Heterotopic ossification (HO) recurrence after joint surgery is always a disturbing problem for patients and surgeons. Our study was performed to assess the efficacy and safety of celecoxib in preventing the recurrence of HO after open arthrolysis for post-traumatic elbow stiffness.

METHODS

We retrospectively studied 152 patients with stiff elbows caused by post-traumatic HO. After surgery, 77 patients received celecoxib (200 mg once daily) for 28 days, whereas 75 did not. Radiographic evaluation was performed at 3, 6, and 9 months postoperatively. Univariate and multivariate analyses were performed to determine which factors affected HO recurrence.

RESULTS

HO was both more common and more severe in the no-celecoxib group than in the celecoxib group at 3, 6, and 9 months after surgery. A significant difference was observed between the 2 groups in terms of postoperative extension (P = .030), flexion (P = .008), and pronation (P = .005); however, no significant difference in postoperative supination was noted (P = .622). Logistic regression analysis showed that taking celecoxib was the protective factor for HO recurrence, whereas overweight (body mass index > 25) and male gender were the risk factors.

CONCLUSIONS

A short course of celecoxib aids in the prevention of HO recurrence after open arthrolysis for elbow stiffness in adults and could be an effective and safe option.

Short-term use of glucocorticoids and risk of peptic ulcer bleeding: a nationwide population-based case-crossover study

BACKGROUND

Controversy exists regarding glucocorticoids therapy and the risk of peptic ulcer bleeding (PUB).

AIM

The present study was undertaken to determine whether short-term use of glucocorticoids is associated with the occurrence of peptic ulcer bleeding.

METHODS

The records of adult patients hospitalised for newly diagnosed peptic ulcer bleeding from 2000 to 2012 were retrieved from the Taiwan National Health Insurance Research Database, a nationwide population-based registry system. The association between systemic glucocorticoids usage and peptic ulcer bleeding was determined with a conditional logistic regression model comparing cases and controls during time windows of 7, 14 and 28 days using a case-crossover design.

RESULTS

Of the 8894 enrolled patients, the adjusted self-matched odds ratios for peptic ulcer bleeding after exposure to the glucocorticoids were 1.37 (95% CI: 1.12-1.68, P = 0.003) for the 7-day window, 1.66 (95% CI: 1.38-2.00, P < 0.001) for the 14-day window and 1.84 (95% CI: 1.57-2.16, P < 0.001) for the 28-day window. Moderate to high, but not low dose glucocorticoids (methylprednisolone <4 mg/day or its equivalence) were associated with an increased risk of peptic ulcer bleeding. Concomitant use of a nonselective nonsteroidal anti-inflammatory drug (NSAID) or aspirin further elevated the risk. However, it does not eliminate the effect of underlying diseases flare-up that may have placed the patients at risk for peptic ulcer bleeding in this kind of study design.

CONCLUSIONS

Short-term (7-28 days) exposure to glucocorticoids is significantly associated with peptic ulcer bleeding; this risk seems dose-dependent and is higher when nonselective NSAIDs or aspirin are used concurrently.

Safe prescribing of non-steroidal anti-inflammatory drugs in patients with osteoarthritis--an expert consensus addressing benefits as well as gastrointestinal and cardiovascular risks

BACKGROUND

There are several guidelines addressing the issues around the use of NSAIDs. However, none has specifically addressed the upper versus lower gastrointestinal (GI) risk of COX-2 selective and non-selective compounds nor the interaction at both the GI and cardiovascular (CV) level of either class of drugs with low-dose aspirin. This Consensus paper aims to develop statements and guidance devoted to these specific issues through a review of current evidence by a multidisciplinary group of experts.

METHODS

A modified Delphi consensus process was adopted to determine the level of agreement with each statement and to determine the level of agreement with the strength of evidence to be assigned to the statement.

RESULTS

For patients with both low GI and CV risks, any non-selective NSAID (ns-NSAID) alone may be acceptable. For those with low GI and high CV risk, naproxen may be preferred because of its potential lower CV risk compared with other ns-NSAIDs or COX-2 selective inhibitors, but celecoxib at the lowest approved dose (200 mg once daily) may be acceptable. In patients with high GI risk, if CV risk is low, a COX-2 selective inhibitor alone or ns-NSAID with a proton pump inhibitor appears to offer similar protection from upper GI events. However, only celecoxib will reduce mucosal harm throughout the entire GI tract. When both GI and CV risks are high, the optimal strategy is to avoid NSAID therapy, if at all possible.

CONCLUSIONS

Time is now ripe for offering patients with osteoarthritis the safest and most cost-effective therapeutic option, thus preventing serious adverse events which could have important quality of life and resource use implications. Please see related article: http://dx.doi.org/10.1186/s12916-015-0291-x.

Risk of upper gastrointestinal bleeding from different drug combinations

BACKGROUND & AIMS

Concomitant use of nonsteroidal anti-inflammatory drugs (NSAIDs) and low-dose aspirin increases the risk of upper gastrointestinal bleeding (UGIB). Guidelines suggest avoiding certain drug combinations, yet little is known about the magnitude of their interactions. We estimated the risk of UGIB during concomitant use of nonselective (ns)NSAIDs, cyclooxygenase -2 selective inhibitors (COX-2 inhibitors), and low-dose aspirin with other drugs.

METHODS

We performed a case series analysis of data from 114,835 patients with UGIB (930,888 person-years of follow-up) identified from 7 population-based health care databases (approximately 20 million subjects). Each patient served as his or her own control. Drug exposure was determined based on prescriptions of nsNSAIDs, COX-2 inhibitors, or low-dose aspirin, alone and in combination with other drugs that affect the risk of UGIB. We measured relative risk (incidence rate ratio [IRR] during drug exposure vs nonexposure) and excess risk due to concomitant drug exposure (relative excess risk due to interaction [RERI]).

RESULTS

Monotherapy with nsNSAIDs increased the risk of diagnosis of UGIB (IRR, 4.3) to a greater extent than monotherapy with COX-2 inhibitors (IRR, 2.9) or low-dose aspirin (IRR, 3.1). Combination therapy generally increased the risk of UGIB; concomitant nsNSAID and corticosteroid therapies increased the IRR to the greatest extent (12.8) and also produced the greatest excess risk (RERI, 5.5). Concomitant use of nsNSAIDs and aldosterone antagonists produced an IRR for UGIB of 11.0 (RERI, 4.5). Excess risk from concomitant use of nsNSAIDs with selective serotonin reuptake inhibitors (SSRIs) was 1.6, whereas that from use of COX-2 inhibitors with SSRIs was 1.9 and that for use of low-dose aspirin with SSRIs was 0.5. Excess risk of concomitant use of nsNSAIDs with anticoagulants was 2.4, of COX-2 inhibitors with anticoagulants was 0.1, and of low-dose aspirin with anticoagulants was 1.9.

CONCLUSIONS

Based on a case series analysis, concomitant use of nsNSAIDs, COX-2 inhibitors, or low-dose aspirin with SSRIs significantly increases the risk of UGIB. Concomitant use of nsNSAIDs or low-dose aspirin, but not COX-2 inhibitors, with corticosteroids, aldosterone antagonists, or anticoagulants produces significant excess risk of UGIB.

Synergistic antinociceptive effect and gastric safety of the combination of docosahexaenoic acid and indomethacin in rats

The use of analgesics is limited by the presence of significant adverse side effects. Thus, combinations of non-steroidal anti-inflammatory drugs (NSAIDs) with other antinociceptive agents are frequently used to decrease these adverse reactions. The aims of this work were to evaluate the antinociceptive interaction of the systemic administration of the combination of DHA and indomethacin through an isobolographic analysis of the theoretical and experimental antinociceptive effect and to demonstrate the gastric safety of the mixture compared with indomethacin alone. Female Wistar rats were orally administered indomethacin (1-10 mg/kg), DHA (100-300 mg/kg), or the DHA-indomethacin mixture at a fixed-ratio combination (1:1, 1:3, 3:1), and the antinociceptive effects of these treatments were evaluated through the formalin (1%) test. An isobolographic analysis was performed to characterize the antinociceptive interaction between DHA and indomethacin. The degree of gastric injury in all of the rats was determined 1 h after the formalin test. The theoretical ED₃₀ values (Zadd) for the 1:1, 1:3, and 3:1 combinations were 73.48 ± 8.96, 37.75 ± 4.50, and 109.2 ± 13.43 mg/kg, p.o., respectively, and the experimental ED30 values (Zexp) were 43.63 ± 5.18, 13.13 ± 1.61, and 54.20 ± 6.53, respectively. The isobolographic analysis showed that the three fixed-ratio combinations studied exhibited a synergistic interaction. Furthermore, the gastric damage induced by indomethacin was abolished when this drug was combined with DHA. These data suggest that the systemic administration of the DHA-indomethacin combination induces a synergistic and gastric safety effect.

Nonsteroidal anti-inflammatory drug gastropathy: new avenues for safety

Chronic oral or systemic nonselective nonsteroidal anti-inflammatory drug (NSAID) therapy, ubiquitously used by physicians to treat osteoarthritis-associated pain, is associated with a wide range of symptomatic adverse events, the most frequent and serious of which is gastropathy. Although cardiovascular and renal problems are a very real concern, they are significantly less frequent. These complications can be life-threatening in at-risk populations such as older adults, who are common users of long-term oral systemic NSAID therapy. Topical NSAID formulations deliver effective doses of analgesics directly to the affected joints, thereby limiting systemic exposure and potentially the risk of systemic adverse events, such as gastropathy and serious cardiovascular events. There are currently two topical NSAIDs approved by the US Food and Drug Administration for osteoarthritis-associated pain, as well as for the signs and symptoms of osteoarthritis. This review discusses the relative safety, and the gastrointestinal, cardiovascular, and renal risks of chronic oral or systemic NSAID therapy and topical NSAID formulations in patients with osteoarthritis.

Synergistic effect of the interaction between naproxen and citral on inflammation in rats

The combination of non-steroidal anti-inflammatory drugs with herbs having analgesic effects can increase their antinociceptive activity and limit their side effects. The aim of the present study was to examine the effects on inflammation and gastric injury in rats resulting from the interaction between naproxen and citral. Naproxen, citral, or fixed-dose naproxen-citral combinations were administered orally and their anti-inflammation (carrageenan-induced paw edema) and gastric damage were assessed in rats. The pharmacological interaction type was evaluated by the isobolographic analysis. Naproxen, citral, or combinations of naproxen and citral produced anti-inflammatory effects. The sole administration of naproxen produced significant gastric damage, but this effect was not obtained with either citral or combinations. ED(30) values were estimated for the individual drugs, and isobolograms were constructed. The derived theoretical ED(30) for the anti-inflammatory effect was 504.4 mg/kg; this was significantly higher than the observed experimental value (190.6 mg/kg). These results indicate that a synergistic interaction underlies the anti-inflammatory effect. The data suggests that the naproxen-citral combination can interact and to produce minor gastric damage and may have therapeutic advantages for the clinical treatment of inflammation.

Gastroprotection and effect of the simultaneous administration of Cuachalalate (Amphipterygium adstringens) on the pharmacokinetics and anti-inflammatory activity of diclofenac in rats

This work aimed to study the effect of Cuachalalate methanol extract (CME) on the anti-inflammatory activity and pharmacokinetics of diclofenac sodium, a frequently prescribed non-steroidal antiinflammatory drug (NSAID). The gastroprotective effect of CME on the gastric injury induced by diclofenac was studied in rats. CME showed a gastroprotective effect of 15.7% at 1 mg kg−1 and 72.5% at dose of 300 mg kg−1. Omeprazole, used as anti-ulcer reference drug, showed gastroprotective effects of 50–89.7% at doses tested (1–30 mg kg−1). The value of the 50% effective dose for the anti-inflammatory effect of diclofenac sodium (ED50 = 1.14 ± 0.23 mg kg−1) using carrageenaninduced rat paw oedema model, was not modified by the concomitant administration of 30 or 100 mg kg−1 of CME. The effect of CME (30, 100 and 300 mg kg−1, p.o.) on the pharmacokinetics of diclofenac sodium was studied. It was observed that the simultaneous administration of diclofenac sodium and 300 mg kg−1 of CME decreased significantly the values of Cmax (7.08 ± 1.42 μg mL−1) and AUC (12.67 ± 2.97 μg h mL−1), but not the value of tmax (0.13 (0.1–0.25) h) obtained with the administration of diclofenac alone. The simultaneous administration of 30 or 100 mg kg−1 of CME did not modify the pharmacokinetic parameters of diclofenac. The experimental findings in rats suggest that CME at doses lower than 100 mg kg−1 protects the gastric mucosa from the damage induced by diclofenac sodium without altering either the anti-inflammatory activity or the pharmacokinetics of this NSAID.

Selective COX-2 inhibitor versus nonselective COX-1 and COX-2 inhibitor in the prevention of heterotopic ossification after total hip arthroplasty: a meta-analysis of randomised trials

Whether selective cyclo-oxygenase-2 (COX-2) inhibitors are equally effective compared to nonselective NSAIDs for the prevention of heterotopic ossification (HO) after total hip arthroplasty (THA) is still unclear. We carried out a comprehensive search strategy, in which only randomised controlled trials were included. Two reviewers independently assessed methodological quality and extracted outcome data. Analyses were performed using Stata version 10.0. Four eligible randomised controlled trials totalling 808 patients were included. Meta-analysis results showed that no statistically significant difference was found in overall incidence of HO (RR 1.08; 95% CI 0.71-1.64), incidence of moderate severe HO (Brooker II and III) (RR 0.83; 95% CI 0.48-1.42) and any grade of Brooker classification between two groups. In summary, the selective COX-2 inhibitors are equally effective as nonselective NSAIDs for the prevention of HO after THA. Considering the gastrointestinal side effects of nonselective NSAIDs, we recommend selective COX-2 inhibitors for the prevention of HO after THA. However, future well-designed, randomised controlled trials are still needed to further confirm our results.

Cost-utility of celecoxib use in different treatment strategies for osteoarthritis and rheumatoid arthritis from the Quebec healthcare system perspective

OBJECTIVE

To assess the cost-utility of celecoxib in three treatment strategies for arthritis in Quebec, considering both upper gastrointestinal (GI) and cardiovascular (CV) events.

METHODS

A Markov analytic framework was used to model patients with osteoarthritis and rheumatoid arthritis at low/average and high risk of GI and CV toxicity over 5 years with monthly cycles. Treatment strategies were modelled in line with Canadian clinical practice. In first-line treatment, patients started on celecoxib; second-line, patients started on a non-selective non-steroidal anti-inflammatory drug (NSAID) and switched to celecoxib after a first GI event; third-line, patients started on a non-selective NSAID, added a proton pump inhibitor (PPI) after a first GI event, and switched to celecoxib after a second GI event (while maintaining the PPI). Model inputs were determined through comprehensive literature searches (MEDLINE and EMBASE) from 1995 to 2006. Included studies evaluated GI (dyspepsia, uncomplicated and complicated ulcers, death) and CV (myocardial infarction, stroke, death) events. Drug and procedure costs were derived from Canadian published sources (Can$2005).

RESULTS

Total costs per patient for celecoxib first-, second-, and third-line treatment were Can$4,790, $3,390, and $3,466, and total quality-adjusted life-years (QALY) were 3.251, 3.231, and 3.230, respectively. In all risk categories, celecoxib second-line was less costly and as effective as celecoxib third-line, producing savings to the healthcare system. Although celecoxib first-line generated incremental expenditures versus celecoxib second-line, it was also more effective. The resulting cost-utility ratio for the high-risk population was Can$54,696/QALY. Based on this analytical approach, a treatment strategy where celecoxib is used before the combination of a non-selective NSAID plus a PPI possesses cost advantages for the Quebec provincial drug programme. One-way sensitivity analysis (varying GI and CV event rates, utilities, and cost) generally showed second-line treatment with celecoxib as the dominant strategy compared with third-line treatment with celecoxib.

CONCLUSION

Although effectiveness of second- and third-line celecoxib use is similar, total cost is lower for second-line. These results suggest that the use of celecoxib before the combination of a non-selective NSAID plus a PPI is relatively cost-effective in the treatment of arthritis pain and support the full benefit listing of celecoxib in Quebec's drug programme.

Impact of patient sample on costs of events in pharmacoeconomic models

Pharmacoeconomic guidelines have focused on improving the measurement of effectiveness, but have largely ignored the assessment of cost inputs. We explored differences in adverse event cost estimates derived from three different sources in a case study of selective COX2 NSAIDs. We found substantial differences in costs of adverse events across data sources. We also determined that treatment costs associated with adverse events differed substantially based upon inclusion/exclusion criteria. Health services researchers should be deliberate in the choice of adverse event treatment costs that are used in decision analytic models. Future guidelines should seek to delineate best practices for cost calculations.

Bleeding peptic ulcer in the elderly: risk factors and prevention strategies

Peptic ulcer bleeding is a frequent and dramatic event with both a high mortality rate and a substantial cost for healthcare systems worldwide. It has been found that age is an independent predisposing factor for gastrointestinal bleeding, with the risk increasing significantly in individuals aged>65 years and increasing further in those aged>75 years. Indeed, bleeding incidence and mortality are distinctly higher in elderly patients, especially in those with co-morbidities. NSAID therapy and Helicobacter pylori infection are the most prevalent aetiopathogenetic factors involved in peptic ulcer bleeding. The risk of bleeding seems to be higher for NSAID- than for H. pylori-related ulcers, most likely because the antiplatelet action of NSAIDs impairs the clotting process. NSAID users may be classified as low or high risk, according to the absence or presence of one or more of the following factors associated with an increased risk of bleeding: co-morbidities; corticosteroid or anticoagulant co-therapy; previous dyspepsia, peptic ulcer or ulcer bleeding; and alcohol consumption. Different types of NSAIDs have been associated with different bleeding risk, but no anti-inflammatory drug, including selective cyclo-oxygenase (COX)-2 inhibitors, is completely safe for the stomach. Furthermore, even low-dose aspirin (acetylsalicylic acid) [<325 mg/day] and a standard dose of non-aspirin antiplatelet treatment (clopidogrel or ticlopidine) have been found to cause bleeding and mortality. No clear risk factor favouring H. pylori-related ulcer bleeding has been identified. Peptic ulcer bleeding prevention remains a challenge for the physician, but data are now available on use of a safer and cheaper strategy for both low- and high-risk patients. Unfortunately, despite the fact that several society and national guidelines have been formulated, these are poorly followed in clinical practice. Proton pump inhibitor (PPI) or misoprostol therapy and H. pylori eradication in NSAID-naive patients are the most commonly proposed strategies. Selective COX-2 inhibitor therapy in high-risk patients has also been suggested, but concerns over the possible cardiovascular adverse effects of some of these agents should be taken into account. Moreover, switching to selective COX-2 inhibitors in patients with previous bleeding is not completely risk free, and concomitant PPI therapy is also needed. H. pylori eradication is mandatory in all patients with peptic ulcer, and such an approach has been found to be significantly superior to PPI maintenance therapy. H. pylori eradication is frequently achieved with sequential therapy in elderly patients with peptic ulcer. In conclusion, upper gastrointestinal bleeding is a dramatic event with a high mortality rate, particularly in the elderly. Some effective preventative strategies are now available that should be implemented in clinical practice.

Viscosupplementation with hyaluronans for osteoarthritis of the knee: clinical efficacy and economic implications

Treatment with intra-articular viscosupplementation with hyaluronan (hyaluronic acid) and its derivatives is an important component of the management of osteoarthritis (OA) of the knee. Several intra-articular hyaluronan formulations are now available that vary in their physical properties, duration of effect and treatment schedules. Although aspects regarding their mechanism of action are not completely understood, numerous clinical trials, systematic reviews and meta-analyses have confirmed the efficacy of intra-articular hyaluronan therapies for relieving OA-related pain and improving joint function. Data indicate that intra-articular hyaluronan preparations provide OA pain relief that is comparable to or greater than that observed with conventional treatment, NSAID medications, intra-articular corticosteroids, arthroscopic lavage, physical therapy and exercise. Other studies indicate that multiple courses of hyaluronan are effective. Intra-articular hyaluronan formulations are well tolerated and are associated with a low incidence of adverse effects, usually localised to the injected joint. Local adverse events associated with intra-articular hyaluronan products are typically mild to moderate in severity, benign and transient, although their aetiology is unknown. The cost effectiveness of intra-articular hyaluronan has been demonstrated, but only in a limited number of studies. Cost savings with intra-articular hyaluronan can also be realised with reduction of NSAID medication use and the possibility of delaying total knee replacement, which can reduce the need for costly revision procedures. Because different intra-articular hyaluronan formulations require different numbers of injections and office visits, are associated with variable treatment costs, and provide varying degrees of efficacy, not all intra-articular hyaluronan formulations may be equally cost effective over time.