A cost-utility analysis of treatment options for inguinal hernia in 1,513,008 adult patients Stylopoulos N, Gazelle G S, Rattner D W

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1 A cost-utility analysis of treatment options for inguinal hernia in 1,513,008 adult patients Stylopoulos N, Gazelle G S, Rattner D W Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Four treatment options for inguinal hernia were examined. These were open mesh repair (OMR), open non-mesh repair (ONMR), laparoscopic repair (LR), and expectant management (EM). Type of intervention Treatment. Economic study type Cost-utility analysis. Study population The study population comprised a hypothetical cohort of patients undergoing inguinal hernia repair, based on 1,513,008 hernia repairs in the USA for 1996 and 1997 (total for USA over this period). Setting The setting was a hospital. The economic study was carried out in the USA. Dates to which data relate The effectiveness evidence came from studies published between 1977 and The resource use data were estimated in part from 1997 to The price year was Source of effectiveness data The effectiveness data were derived from a synthesis of published studies, augmented with authors' assumptions and/or estimates. Modelling A Markov model was used to determine the costs and benefits associated with the four treatment options in a cohort of 1,513,008 patients who had undergone inguinal hernia repair in the USA in 1996 and A simplified version of the decision tree was reported. Each patient's life was simulated until death. Hernia repair was performed either on an ambulatory basis or in the hospital. Clearly, a proportion of ambulatory patients were admitted to the hospital. The operation had three outcomes, namely, surgical mortality, uneventful recovery, and surgical morbidity. All possible major complications were modelled. These included wound abscess, haematoma or seroma, hydrocele, orchitis, and chronic pain. The patients could die due to age-, gender- or race-related factors, or might experience hernia recurrence (undergoing another emergency or elective operation). Otherwise, the patients remained in the "post-hernia without recurrence" state, unless they died or developed a recurrence. Patients in the EM arm, experienced only three transitions. They remained in this state until they died due to age-, gender- or race-related factors, or they developed symptoms requiring emergency operation. The length of a cycle was unclear. Page: 1 / 7

2 Outcomes assessed in the review The outcomes estimated from the literature were: the probabilities of hospital admission and surgical mortality (both estimated using two logistic regression models); the probabilities associated with the development and treatment of postoperative complications; the probability of patients with recurrent hernias not undergoing another operation; the probability of developing symptoms requiring emergency intervention; and utility values. The probabilities pertaining to postoperative complications included: wound abscess, haematoma or seroma, hydrocele, orchitis, chronic persistent symptoms, the rate of haematoma or seroma cases requiring intervention, the percentage of hydrocele cases requiring aspiration, the hydrocele aspiration failure rate, the percentage of patients with chronic persistent symptoms seeking medical advice, and the hernia recurrence rate Study designs and other criteria for inclusion in the review It was not explicitly stated whether a systematic review of the literature had been undertaken. However, several clinical trials and three large administrative databases were used. Sources searched to identify primary studies Not stated. Criteria used to ensure the validity of primary studies Selecting only clinical trials and three large administrative databases ensured the validity of the primary studies. The databases used were the National Survey of Ambulatory Surgery (NSAS), the National Hospital Discharge Survey (NHDS), and the 1997 Nationwide Inpatient Sample (NIS). The use of these sources led to a very large sample size (1,513,008 adult patients), including the total number of patients who underwent inguinal hernia repair in the USA in 1996 and Methods used to judge relevance and validity, and for extracting data Not stated. Page: 2 / 7

3 Number of primary studies included Fifty-one clinical trials and three administrative databases provided the data. Some other sources (5 primary studies) were also used. Methods of combining primary studies It appears that the primary estimates have been combined using narrative methods. Investigation of differences between primary studies Not stated. Results of the review The probabilities of hospital admission and surgical mortality depended on age-, gender- and race-related factors. In general, in the whole sample, 2.2% of the patients who were scheduled to undergo an ambulatory hernia repair were eventually admitted to the hospital. In 57.4% of in-hospital cases, the admission type was characterised as urgent or emergency, while the remaining 42.6% of the in-hospital repairs were performed as elective repairs. The mortality rate for the in-hospital performed inguinal hernia repairs was 1%. The group of emergency admissions had a mortality rate of 1.4%, while the corresponding rate for elective surgery was 0.6%. The rate of wound abscess was 0.12% (range: ) with LR, 0.42% (range: ) with OMR, and 0.58% (range: ) with ONMR. The rate of haematoma or seroma was 5.92% (range: ) with LR, 6.90% (range: ) with OMR, and 4.86% (range: ) with ONMR. The rate of hydrocele was 0.35% (range: ) with LR, 0.48% (range: ) with OMR, and 0.10% (range: ) with ONMR. The rate of orchitis was 0.39% (range: ) with LR, 0.30% (range: ) with OMR, and 0.34% (range: ) with ONMR. The rate of chronic persistent symptoms was 1.31% (range: ) with LR, 2.46% (range: ) with OMR, and 4.89% (range: ) with ONMR. The rate of haematoma or seroma cases requiring interventions was 10%. The proportion of hydrocele cases requiring aspiration was 15% and the hydrocele aspiration failure rate was 39% (range: ). The proportion of patients with chronic persistent symptoms seeking medical advice was 4.50% (range: ). The probability of early hernia recurrence (within 2 years) was 2.195% with LR, 2.329% with OMR, and 4.737% with ONMR. The hernia recurrence rate after 2 years was estimated using a mathematical formula for the recurrence rate. The probability of patients with recurrent hernias not undergoing another operation was 25% (range: 0-100). The annual risk of developing symptoms requiring emergency intervention was 0.29%, while the 5-year risk of strangulation was 8.6%. The quality of life weights were: Page: 3 / 7

4 for current health status, 0.76 for a 45-year-old patient (both male and female), and 0.61 for a man and 0.67 for a woman in the case of an 85-year-old patient; for chronic pain, 85% of current health status (range: 83-90); for primary hernia (watchful waiting), 95% of current health status (range: ); for recurrent hernia (no redo operation), same as current health status; and for dead, 0. Methods used to derive estimates of effectiveness Some assumptions were made when deriving the estimates of effectiveness. Estimates of effectiveness and key assumptions It was assumed that all patients requiring emergency surgery underwent ONMR, while all patients with recurrences underwent OMR. In addition, each patient in the model could undergo an LR only once. The quality of life of a patient with recurrent hernia who chose not to undergo reoperation was assumed to be similar to the quality of life of a healthy individual of the same age and gender. Measure of benefits used in the economic analysis The summary benefit measure used was the number of quality-adjusted life-years (QALYs). No discounting appears to have been applied. Utility weights and survival data were derived from the literature, as reported already. The Quality of Well Being Index was used to derive the utility values. Direct costs An annual discount rate of 3% was applied as the long-term costs were estimated. The unit costs were reported, but there was limited information on resource use. The health services included in the economic evaluation were physician fees, facility costs, nerve block, medications, and home visits. A detailed breakdown of the cost items was presented. The cost/resource boundary of the third-party payer was adopted for the analysis of the direct costs. The unit costs were estimated on the basis of Medicare reimbursement rates and wholesale prices. The total costs were estimated using modelling. Resource use data were based on experts' assumptions and published evidence. The costs were presented in 2002 values using the gross domestic product deflator. Statistical analysis of costs The costs were treated deterministically in the base-case. Indirect Costs The indirect costs were included, which was appropriate given the societal perspective adopted. The patients' opportunity costs were evaluated from historical income tables obtained from the US Census Bureau. The unit cost of one workday was reported, but details of the quantities of resources used were not. The source of the resource use data was unclear. An annual discount rate of 3% was applied and the costs were presented in 2002 values. Currency US dollars ($). Sensitivity analysis Page: 4 / 7

5 One- and two-way sensitivity analyses were carried out to assess the impact of base-case assumptions on the estimated cost-effectiveness ratios. Estimated benefits used in the economic analysis The QALYs associated with each option were 6.35 with EM, 9.04 with LR, with OMR, and with ONMR. Therefore, the estimated additional QALYs with LR were compared with OMR, and 0.5 compared with ONMR. Cost results The costs associated with each option were $2,466 with EM, $4,086 with LR, $4,290 with OMR, and $6,200 with ONMR. Therefore, the cost of LR was 5% less than OMR and 35% less than ONMR. Synthesis of costs and benefits Incremental cost-effectiveness ratios were calculated to combine the costs and benefits of the alternative treatment options. Under base-case assumptions, LR dominated OMR and ONMR since it was both less costly and more effective. In the comparison with EM, the incremental cost per QALY was $605 with LR, $697 with OMR, and $1,711 with ONMR. The sensitivity analyses revealed that ambulatory facility costs and recurrence rates had the greatest impact on the estimated cost-effectiveness ratios. In particular, LR remained the preferred strategy as long as the facility cost of LR was lower than $2,460 (in the base-case it was estimated at $2,351). However, when the cost was higher than this threshold, OMR became the most cost-effective option. Also, at a recurrence rate of LR higher than 6.2% (in the basecase it was 2.192%), OMR dominated LR. Authors' conclusions From a societal perspective, laparoscopic repair (LR) was a cost-effective strategy in comparison with expectant management (EM), open mesh repair (OMR) and open non-mesh repair (ONMR). CRD COMMENTARY - Selection of comparators The rationale for the choice of the comparators was clear since it covered all possible strategies for the management of inguinal hernia. The authors noted that there was no distinction between transabdominal preperitoneal and the totally extraperitoneal repair. You should decide whether they are valid comparators in your own setting. Validity of estimate of measure of effectiveness The analysis of effectiveness was based on data derived from completed studies, but it was unclear whether a systematic review of the literature had been undertaken. Clinical trials and three administrative databases were the main sources of the data and this resulted in a very large sample size. The primary estimates were combined using narrative methods. Some assumptions were also made and the issue of uncertainty was investigated in the sensitivity analysis. Validity of estimate of measure of benefit The benefit measure, QALYs, was appropriate as it reflected the impact of the interventions on quality of life and survival. Discounting was not applied as recommended in US guidelines for economic evaluation. Changes in the quality of life estimates did not affect the conclusions of the analysis. The use of QALYs means that comparisons with the benefits of other health care interventions would be possible. Page: 5 / 7

6 Validity of estimate of costs The authors adopted a societal perspective and included all the relevant categories of costs in the analysis. The information on the indirect costs was limited. A detailed breakdown of the cost items included in the analysis of the direct costs was provided. The price year was provided, which will simplify reflation exercises in other settings. The source of the cost data was reported for all categories. The costs were treated deterministically in the base-case but were then varied in the sensitivity analysis. Other issues The authors stated that their findings were in accordance with those from other published studies. However, the issue of the generalisability of the study results to other settings was not addressed. This might have reduced the external validity of the analysis, although sensitivity analyses were carried out to deal with the issue of uncertainty. The study referred to patients undergoing inguinal hernia repair and this was reflected in the authors' conclusions. Both the limitations and strengths of the analysis were highlighted. Implications of the study The authors suggested "greater efforts to make laparoscopic herniorrhaphy easier to perform could ultimately reduce health care costs". Source of funding None stated. Bibliographic details Stylopoulos N, Gazelle G S, Rattner D W. A cost-utility analysis of treatment options for inguinal hernia in 1,513,008 adult patients. Surgical Endoscopy and Other Interventional Techniques 2003; 17(2): PubMedID DOI /s z Other publications of related interest Healthcare Cost and Utilization Project Nationwide Inpatient Sample (NIS) (CD-ROM). Release 6. Rockville (MD): Agency for Healthcare Research and Quality. National Hospital Discharge and Ambulatory Surgery Data (1996, 1997). Available from: URL: (accessed March 2005). Indexing Status Subject indexing assigned by NLM MeSH Adult; Aged; Ambulatory Care /economics; Cost-Benefit Analysis; Decision Support Techniques; Digestive System Surgical Procedures /economics /mortality; Female; Hernia, Inguinal /economics /surgery; Hospitalization /statistics & numerical data; Humans; Laparoscopy /economics /mortality; Logistic Models; Male; Markov Chains; Middle Aged; Models, Economic; Monte Carlo Method; Quality of Life; Quality-Adjusted Life Years; Recurrence; Risk Assessment; Sex Distribution; Survival Rate; Treatment Outcome AccessionNumber Page: 6 / 7

7 Powered by TCPDF ( Date bibliographic record published 31/03/2005 Date abstract record published 31/03/2005 Page: 7 / 7