The Epidemiology of Appendicitis and Appendectomy in South Korea: National Registry Data

Background

Appendicitis is one of the most frequent acute surgical conditions of the abdomen, and appendectomy is one of the most commonly performed operations in the world. However, epidemiological data on appendicitis have not been reported for South Korean or East Asian populations.

Methods

We analyzed the epidemiological features and lifetime risk of appendicitis and appendectomy in South Korea using data collected for the national health insurance database from 2005 through 2007.

Results

Appendectomy was performed in 59.70% of inpatients diagnosed with appendicitis. The overall incidences of appendicitis, total appendectomy, and perforated appendectomy were 22.71, 13.56, and 2.91 per 10 000 population per year, respectively. The incidence of appendicitis and appendectomy showed clear seasonality, with a peak in summer. The standardized lifetime risks of appendicitis and appendectomy were constant from 2005 through 2007. A life table model suggests that the lifetime risk of appendicitis is 16.33% for males and 16.34% for females, and that the lifetime risk of appendectomy is 9.89% for males and 9.61% for females.

Conclusions

As compared to results obtained in research on Western populations, appendicitis and appendectomy had a similar perforation rate and seasonality, but a higher overall incidence, in South Koreans. Between 2005 and 2007, the incidence of appendicitis and appendectomy was constant. Overall, an estimated 15 incidental appendectomies are performed to prevent 1 inpatient with suspected appendicitis, and 26 incidental appendectomies are performed to prevent 1 appendectomy. Incidental appendectomy may have greater preventive value in Koreans.Key words: appendectomy, appendicitis, epidemiology, health insurance claims     

The epidemiology of appendicitis and appendectomy in the United States

To describe the epidemiology of appendicitis and appendectomy in the United States, the authors analyzed National Hospital Discharge Survey data for the years 1979-1984. Approximately 250,000 cases of appendicitis occurred annually in the United States during this period, accounting for an estimated 1 million hospital days per year. The highest incidence of primary positive appendectomy (appendicitis) was found in persons aged 10-19 years (23.3 per 10,000 population per year); males had higher rates of appendicitis than females for all age groups (overall rate ratio, 1.4:1). Racial, geographic, and seasonal differences were also noted. Appendicitis rates were 1.5 times higher for whites than for nonwhites, highest (15.4 per 10,000 population per year) in the west north central region, and 11.3% higher in the summer than in the winter months. The highest rate of incidental appendectomy was found in women aged 35-44 years (43.8 per 10,000 population per year), 12.1 times higher than the rate for men of the same age. Between 1970 and 1984, the incidence of appendicitis decreased by 14.6%; reasons for this decline are unknown. A life table model suggests that the lifetime risk of appendicitis is 8.6% for males and 6.7% for females; the lifetime risk of appendectomy is 12.0% for males and 23.1% for females. Overall, an estimated 36 incidental procedures are performed to prevent one case of appendicitis; for the elderly, the preventive value of an incidental procedure is considerably lower.     

Incidence and case fatality rates for acute appendicitis in California. A population-based study of the effects of age

In 1984, 24,794 appendectomies and abscess drainage procedures were performed for acute appendicitis in California hospitals. Analysis of hospital discharge abstracts revealed age- and sex-specific incidence rates and in-hospital case fatality rates for acute appendicitis lower than previously reported. In persons aged 60 years and older, the case fatality rate for nonperforating appendicitis with appendectomy was 0.7% and for perforating appendicitis and abscess 2.4%. Surgery was delayed beyond the day of admission in 21% of persons aged 40-59 years, 29% of persons aged 60-79 years, and 47% of persons aged 80 years and over. The proportion of cases with perforation increased from 22% to 75% between ages 20 and 80 years. The population incidence of perforating appendicitis changed little after age 20 years, while the incidence of nonperforating cases declined sharply. The high proportion of appendicitis cases with perforation among the elderly may be due to the decreased incidence of nonperforating appendicitis in the elderly and not to a greater propensity for perforation, as previously proposed. Most elderly in California receive timely surgery for appendicitis and tolerate it better than previously reported. Diminished tolerance for intra-abdominal infection may be the primary determinant of the increase in case fatality with age.     

Interval appendectomy as indicated rather than as routine therapy: fewer operations and shorter hospital stays

OBJECTIVE: To determine whether performing interval appendectomy only as indicated reduces the number of interval appendectomies, morbidity and duration of hospital stay compared with the conventional approach of routine interval appendectomy. DESIGN: Prospective and comparison with a historical control group. METHODS: In the period May 2000-December 2002 46 patients were prospectively followed after conservative treatment for an appendiceal mass or abscess. Interval appendectomy was performed only as indicated. Study endpoints were the number of patients who were symptom-free at the last outpatient visit and the number ofinterval appendectomies or emergency appendectomies performed for symptoms or acute appendicitis, respectively. Morbidity and duration of hospital stay were compared with a consecutive historical group of patients who had undergone routine interval appendectomy in the period 1994-April 2000. RESULTS: Appendectomy was avoided in 29 of the 46 patients. The median total admission time was 9 days versus 12 days for patients who had undergone routine interval appendectomy. Three patients in each group had complications. CONCLUSION: By performing interval appendectomy only as indicated for persistent pain in the lower right abdomen or emergency appendectomy for acute appendicitis, the number of appendectomies was reduced by 63% and the duration of hospital stay was reduced by 4 days.     

The Effects of Laparoscopic Surgery and Nosocomial Infections on the Cost of Care: Evidence from Three Common Surgical Procedures

Objective:  To examine the cost of care for laparoscopic versus open surgery and the added cost of nosocomial infections for three common surgical procedures: cholecystectomy, hysterectomy, and appendectomy.
Methods:  The Cardinal Health database repository was utilized to extract reimbursement data for laparoscopic and open cholecystectomy, hysterectomy, and appendectomy surgical procedures. Utilizing a 22-hospital sample and a Health Insurance Portability and Accountability Act compliant clinical data extraction technique, the Cardinal Health database repository produced a Nosocomial Infection Marker to identify and track nosocomial infection rates for these procedures. ICD-9 codes were utilized to identify 10,731 patients who had undergone these procedures between September 2004 and December 2006. Multivariable linear regression models were estimated to isolate the effects of laparoscopic versus open surgery and nosocomial infections on the cost of care.
Results:  Laparoscopic surgery significantly reduces the overall cost of care for cholecystectomies, hysterectomies, and appendectomies. Controlling for the cost of nosocomial infection, incremental cost savings from laparoscopic versus open surgery for all three procedures average $1608. Cholecystectomy has the largest savings ($3299), followed by hysterectomy ($1385) and appendectomy ($1032). These cost savings in part reflect that patients undergoing laparoscopic procedures have shorter lengths of stay. In contrast, nosocomial infection increases costs substantially for each surgery type, raising costs for cholecystectomy by $4794, hysterectomy by $4528, and appendectomy by $6108.
Conclusion:  The cost of care for laparoscopic surgery is lower than open surgery for cholecystectomy, hysterectomy, and appendectomy. This conclusion is based on actual hospital reimbursement data.     

Cost-effectiveness of tuberculosis screening and observed preventive therapy for active drug injectors at a syringe-exchange program

This study examined whether costs associated with tuberculosis (TB) screening and directly observed preventive therapy (DOPT) among drug injectors attending a syringe exchange are justified by cases and costs of active TB cases prevented and examined the impact of monetary incentives to promote adherence on cost-effectiveness. We examined program costs and projected savings using observed adherence and prevalence rates and literature estimates of isoniazid (INH) preventive therapy efficacy, expected INH hepatoxicity rates, and TB treatment costs; we conducted sensitivity analyses for a range of INH effectiveness, chest X-ray (CXR) referral adherence, and different strategies regarding anergy among persons affected with human immunodeficiency virus (HIV). For 1,000 patients offered screening, incorporating real observed program adherence rates, the program would avert $179,934 in TB treatment costs, for a net savings of $123,081. Assuming a modest risk of TB among HIV-infected anergic persons, all strategies with regard to anergy were cost saving, and the strategy of not screening for anergy and not providing DOPT to HIV-infected anergic persons resulted in the greatest cost savings. If an incentive of $25 per person increased CXR adherence from the observed 31% to 50% or 100%, over a 5-year follow-up the net cost savings would increase to $170,054 and $414,856, respectively. In this model, TB screening and DOPT at a syringe exchange is a cost-effective intervention and is cost-saving compared to costs of treating active TB cases that would have occurred in the absence of the intervention. This model is useful in evaluating the cost impact of planned program refinements, which can then be tested. Monetary incentives for those referred for screening CXRs would be justified on a cost basis if they had even a modest beneficial impact on adherence.     

An economic analysis of alternatives for childhood immunisation against Haemophilus influenzae type b disease

Abstract: Cost-effectiveness and cost-utility analyses of immunisation strategies against invasive Haemophilus influenzae type b (Hib) disease in Australia were based on a hypothetical birth cohort of 250 000 non-Aboriginal Australian children. The model predicted that, without immunisation, 625 cases of invasive Hib disease would occur in under-five-year-olds, with direct costs of $10.2 million. Universal public sector vaccination beginning before six months of age (6MVAC) prevented 80 per cent of cases; vaccination at 12 months (12MVAC) 62 per cent and at 18 months (18MVAC) 46 per cent At a vaccine cost of $15 per dose, 18MVAC gave the lowest cost per quality-adjusted life year (QALY) over a wide range of model assumptions, with 6MVAC the ‘best’ alternative. The best estimate ($ per QALY) for 6MVAC was $6930 (three doses), for 12MVAC $9136 (two doses) and for 18MVAC $1231 (one dose). The cost per QALY of single dose catch-up immunisation of older children was estimated at $8630 at two years, $27 000 at three years and $117 000 at four years if done at a scheduled visit; these values were increased if an additional medical visit was included. The threshold cost per vaccine dose at which an immunisation program became cost-saving was estimated for 6MVAC, 12MVAC and 18MVAC as $11, $10 and $14. Even under a worst-case scenario, an immunisation program at 6, 12 or 18 months became cost-saving if indirect costs of death were included. Comparison with previous analyses revealed the importance of the incidence and age distribution of disability and assumptions about vaccine administration costs in determining model outcomes.     

Epidemiologic investigation of a Yersinia camp outbreak linked to a food handler

In July 1981, an outbreak of gastroenteritis occurred at a summer diet camp. Of the 455 campers and staff, 35 per cent developed an illness characterized by abdominal pain, fever, diarrhea, and/or nausea and vomiting. A total of 53 per cent experienced abdominal pain. Seven persons were hospitalized, five of whom had appendectomies. Yersinia enterocolitica serogroup 0:8 was isolated from 37 (54 per cent) of 69 persons examined, including the camp cook and three assistants. An epidemiologic investigation demonstrated that illness was associated with consumption of reconstituted powdered milk and/or chow mein . Y. enterocolitica serogroup 0:8 was subsequently isolated from milk, the milk dispenser, and leftover chow mein . Information obtained during the investigation suggested that the Yersinia had been introduced by a food handler during food-processing procedures.     

高龄阑尾炎小切口手术治疗体会

目的总结高龄阑尾炎病人的临床表现,并探讨围手术期的有关问题。方法回顾性分析年龄≥70岁,接受手术治疗的72例阑尾炎患者的临床资料。结果72例高龄患者中,73．6％术前伴有高血压,冠心病,慢性肺病及糖尿病等老年常见病;72例均行小切口阑尾切除术,术后并发症发生率为12．5％,术前伴有其他系统疾病者并发症的发生率（20．8％）显著高于无其他系统疾病者（9．7％）,P〈0．01。结论高龄阑尾炎患者术前伴发疾病多,术后并发症发生率高,应加强围手术期的处理,小切口提高了手术的安全性,优于腹腔镜阑尾切除术,老年人容易接受。     

The cost of antiretroviral therapy in Haiti

Background

Tobacco smoking is a risk factor for age-related macular degeneration, but studies of ex-smokers suggest quitting can reduce the risk.

Methods

We fitted a function predicting the decline in risk of macular degeneration after quitting to data from 7 studies involving 1,488 patients. We assessed the cost-effectiveness of smoking cessation in terms of its impact on macular degeneration-related outcomes for 1,000 randomly selected U.S. smokers. We used a computer simulation model to predict the incidence of macular degeneration and blindness, the number of quality-adjusted life-years (QALYs), and direct costs (in 2004 U.S. dollars) until age 85 years. Cost-effectiveness ratios were based on the cost of the Massachusetts Tobacco Control Program. Costs and QALYs were discounted at 3% per year.

Results

If 1,000 smokers quit, our model predicted 48 fewer cases of macular degeneration, 12 fewer cases of blindness, and a gain of 1,600 QALYs. Macular degeneration-related costs would decrease by $2.5 million if the costs of caregivers for people with vision loss were included, or by $1.1 million if caregiver costs were excluded. At a cost of $1,400 per quitter, smoking cessation was cost-saving when caregiver costs were included, and cost about $200 per QALY gained when caregiver costs were excluded. Sensitivity analyses had a negligible impact. The cost per quitter would have to exceed $77,000 for the cost per QALY for smoking cessation to reach $50,000, a threshold above which interventions are sometimes viewed as not cost-effective.

Conclusion

Smoking cessation is unequivocally cost-effective in terms of its impact on age-related macular degeneration outcomes alone.     

困难型腹腔镜阑尾切除术的原因及处理

目的 探讨困难型腹腔镜阑尾切除术的原因以及术中处理技巧.方法 回顾性分析102例困难型腹腔镜阑尾切除术患者的临床资料.结果 困难原因分别为阑尾周围严重粘连44例、阑尾根部坏疽21例、阑尾解剖位置特殊17例、腹腔内粘连12例、肥胖以及肠道充气8例;96例成功施行腹腔镜阑尾切除术,成功率94.1%(96/102).无肠漏、大出血等严重并发症.结论 阑尾周围严重粘连是常见的困难原因,而阑尾根部坏疽是最难处理的.阑尾残端的处理直接影响到手术的成功率及术后并发症发生.

Abstract：

Objective To study the cause and management of difficult laparoscopic appendectomy.Method A retrospective analysis of 102 difficult laparoscopic appendectomies was performed. Results The associating factors leading to operative difficulty were as follows:adhesion of peri-appendix in 44 cases,gangrene at root of appendix in 21 cases,special location of appendix in 17 cases,abdominal adhesion in 12 cases,obesity and inflatable intestine in 8 cases. Laparoscopic appendectomy was successfully performed in 96 cases(94.1%,96/102) ,and no intestinal leakage or massive hemorrahge occurred. Conclusions Adhesion of peri-appendix is the most common cause in difficult laparoscopic appendectomy,and gangrene at root of appendix is the most difficult one. Reasonable management for appendix stump contributes to successful operation.     

Economic impact of implementing decennial tetanus toxoid,reduced diphtheria toxoid and acellular pertussis (Tdap) vaccination in adults in the United States

BackgroundIn the United States, persons ≥11 years are recommended to receive one dose of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine, followed by decennial tetanus- and diphtheria-toxoid (Td) boosters. Many providers use Tdap instead of Td. We evaluated epidemiologic and economic impacts of replacing Td boosters with Tdap.MethodsWe used a static cohort model to examine replacing Td with Tdap over the lifetime of 4,386,854 adults ≥21 years. Because pertussis is underdiagnosed and true incidence is unknown, we varied incidence from 2.5 cases/100,000 person-years to 500 cases/100,000 person-years. We calculated vaccine and medical costs from claims data. We estimated cost per case prevented and per quality-adjusted life year (QALY) saved; sensitivity analyses were conducted on vaccine effectiveness (VE), protection duration, vaccine cost, disease duration, hospitalization rates, productivity loss and missed work. We did not include programmatic advantages resulting from use of a single tetanus-toxoid containing vaccine.ResultsAt lowest incidence estimates, administering Tdap resulted in high costs per averted case ($111,540) and QALY saved ($8,972,848). As incidence increased, cases averted increased and cost per QALY saved decreased rapidly. With incidence estimates of 250 cases/100,000 person-years, cost per averted case and QALY saved were $984 and $81,678 respectively; at 500 cases/100,000 person-years, these values were $427 and $35,474. In multivariate sensitivity analyses, assuming 250 cases/100,000 person-years, estimated cost per QALY saved ranged from $971 (most favorable) to $217,370 (least favorable).ConclusionsOur findings suggest that replacing Td with Tdap for the decennial booster would result in high cost per QALY saved based on reported cases. However, programmatic considerations were not accounted for, and if pertussis incidence, which is incompletely measured, is assumed to be higher than reported through national surveillance, substituting Tdap for Td may lead to moderate decreases in pertussis cases and cost per QALY.     

Service use and costs for Medicare beneficiaries in risk-based HMOs and CMPs: some interim results from the National Medicare Competition Evaluation.

The Health Care Financing Administration (HCFA) initiated the Medicare Competition Demonstration in 1982 in anticipation of congressional intent to establish a national program. Interim results on the 1984 service use and cost experience of the health maintenance organizations (HMOs) and competitive medical plans (CMPs) participating in the demonstrations indicate that Medicare enrollees in the demonstration experienced a median of 1,951 hospital days per 1,000 person years, 57 per cent of the median of 3,432 days per 1,000 in the local markets from which the plans drew enrollment. Independent practice association (IPA) HMOs experienced higher hospital use rates than staff and group model HMOs. These comparisons are not adjusted for various risk factors, the absence of which were likely to favor the demonstration plans. Plans with lower hospital service use were federally qualified and had been operating for more than five years. The median total annual revenue per enrollee across all plans was $2,312, compared to median annual expenses per enrollee of $2,250. The distribution of median annual expenses per enrollee by major category of expense was: institutional expenses ($1,038/enrollee), medical expenses ($720/enrollee), supplemental services expenses ($154/enrollee), and administrative and other expenses ($295/enrollee). Future analysis, using beneficiary-level data, will examine the impact of the demonstration and the nature and extent of evident biased selection and will compare the quality of care in the demonstrations to that in the fee-for-service sector.     

Simple ligation superior to inversion of the appendiceal stump; a prospective randomized study]

OBJECTIVE. To compare two methods of treatment of the appendix stump after appendectomy for acute appendicitis. DESIGN. A prospective randomised trial of 134 consecutive appendectomies in which the appendix stump was either simply ligated or ligated and doubly invaginated. SETTING. Department of General Surgery, St Joseph Hospital, Veldhoven, the Netherlands. PATIENTS AND METHODS. During a period of 15 months all patients in whom an appendectomy for acute appendicitis was performed were allocated at random to the two groups. The following data were recorded: age, sex, histological diagnosis, hospital stay and occurrence of complications. All patients were followed until 6 months after the operation. The data were analysed statistically with the chi-square-test and the Mann-Whitney test. P less than 0.05 was considered significant. RESULTS. The appendix stump was ligated in 79 patients and invaginated in 55. Both groups were similar with respect to age, sex, degree of appendiceal inflammation, antibiotic treatment and hospital stay. There were significantly more wound infections in the 'invagination' group (p = 0.017). The other complications showed no statistical intergroup difference. CONCLUSION. Simple ligation facilitates and shortens appendectomy. It is a safe procedure, preventing deformation of the caecal wall and possibly reducing the risk of postoperative ileus due to adhesions. We therefore recommend simple ligation as the standard procedure at appendectomy.     

An outbreak of appendectomies in La Désirade, Guadeloupe, August 1995-July 1996

BACKGROUND: In October 1995, over 50 cases of appendectomies among the 1.605 residents of the island La Désirade (Guadeloupe) were reported by the only island clinician to the local health authority. We describe the outbreak investigations which were implemented in order to describe the phenomenon and generate hypotheses on its cause. METHODS: An exhaustive case finding of residents having undergone appendectomy between 10 August 1995 and 22 July 1996 was conducted. We reviewed the medical charts of the cases; read pathology slides; interviewed cases and their families to retrieve detailed clinical history; studied the prevalence of markers of infection and of stool pathogens and analysed water supply quality data. RESULTS: We identified 226 cases of appendectomy (14% of the island population), 40% in May-June 1996, 46% in males and 40% under 15 years of age. Clinical, biological and pathological findings were heterogeneous and did not support the hypothesis of an outbreak of appendicitis. The study of abdominal symptoms in the families of the cases did not support person to person transmission but revealed frequent, subacute or chronic abdominal complaints. The analysis of markers of infection or of stool bacteria and parasites in a self selected sample of the island population was not suggestive. Water supply did not show any bacterial or chemical contamination. CONCLUSION: The investigation of a large outbreak of appendectomies was unable to find a single infectious or toxic origin to a high prevalence of chronic abdominal symptoms in an isolated population. An inappropriate medical answer in an isolated population probably turned heterogeneous complaints into an outbreak with major public health consequences.     

Age- and sex-specific prevalence of scoliosis and the value of school screening programs

A prevalence study of idiopathic scoliosis was conducted among 29,195 children of a community health district in the province of Quebec. The study was designed to determine whether a permanent screening program for idiopathic scoliosis was justified. The prevalence of the condition among school children aged 8 to 15 years was 42.0 per 1,000 in the screened population, 51.9 per 1,000 among girls, and 32.0 per 1,000 among boys. The positive predictive value of the bending test is estimated as 42.8 per cent for scolioses of 5 degrees or more; it is only 6.4 per cent when curves of 15 degrees or more are considered. The average cost of finding one child with a scoliosis of 5 degrees or more is $194. Mass screening for idiopathic scoliosis does not seem to be justified in the present state of knowledge of the disease.     

腹腔镜在军人急性阑尾炎中的应用价值

目的：比较腹腔镜阑尾切除术与传统开腹手术在军人急性阑尾炎治疗中的价值,并进行费用分析。方法对2014年1月至2015年12月间医院手术治疗的军人急性阑尾炎患者111人随机分为腹腔镜组和开腹手术组,收集在院和随访数据,进行统计分析。结果腹腔镜组在手术时间、下床时间、通气时间、术后住院时间、并发症、手术满意度方面均优于开腹手术者,尤其是院外术后半休时间（12．53±2．77天比25．95±4．98天, t ＝15．577, P ＜0．001）差别显著,但腹腔镜组治疗费用较高。结论腹腔镜手术较传统手术具有很多优点,在军人患者中可以有效降低非战斗减员,管理上可采用适当措施控制治疗费用。     

Cost-effectiveness analysis of screening by faecal occult blood testing for colorectal cancer in Australia

Abstract: The incremental costs and effects of annual faecal occult blood test screening in Australia were modelled for a hypothetical cohort of 1000 persons offered screening or not offered screening. Incremental costs and effects were estimated as the differences in direct health care costs (Australian costs) and years of life remaining between the annual-screen group and the control (no screen) group, based on the published results of the Minnesota randomised controlled trial. The cost per life year saved was $24 660. The greatest source of variability in the cost-effectiveness ratio is the effectiveness of screening. The 95 per cent confidence interval for cumulative mortality in the annual-screen group is 3.86 to 7.9 per 1000, assuming the control rate is fixed at 8.83 per 1000. With this confidence interval, the cost per life year saved ranges from $12 695 to $67 848. The cost-effectiveness ratio increases to $48 000 if no mortality benefit is assumed beyond the end of the trial follow-up period, 13 years. The results are sensitive to the cost of colonoscopy (at $400 per colonoscopy, the cost per life year saved is $12 319) and the false-positive rate. The cost-effectiveness of colorectal cancer screening is comparable with that of other screening programs but further evidence is needed on the efficacy of screening. Whether the benefits of colorectal cancer screening outweigh the harm and costs needs to be more certain before more resources are committed to mass screening. Health policy planners should initiate planning for Australian pilot projects in the event that the efficacy of screening is confirmed by two current studies.     

隐瘢痕两孔法经腹腔镜阑尾切除术63例

目的探讨隐瘢痕腹腔镜阑尾切除术的可行性及疗效。方法回顾性分析2007年3月～2012年10月我科接受隐瘢痕腹腔镜阑尾切除术63例的临床资料。结果全部病例经成功手术后,痊愈出院,均无并发症发生。结论隐瘢痕腹腔镜阑尾切除术安全有效,兼具美容效果。     

The economic impact of methicillin-resistant Staphylococcus aureus in Canadian hospitals.

OBJECTIVES: To determine the costs associated with the management of hospitalized patients with methicillin-resistant Staphylococcus aureus (MRSA), and to estimate the economic burden associated with MRSA in Canadian hospitals. DESIGN: Patient-specific costs were used to determine the attributable cost of MRSA associated with excess hospitalization and concurrent treatment. Excess hospitalization for infected patients was identified using the Appropriateness Evaluation Protocol, a criterion-based chart review process to determine the need for each day of hospitalization. Concurrent treatment costs were identified through chart review for days in isolation, antimicrobial therapy, and MRSA screening tests. The economic burden to Canadian hospitals was estimated based on 3,167,521 hospital discharges for 1996 and 1997 and an incidence of 4.12 MRSA cases per 1,000 admissions. SETtING: A tertiary-care, university-affiliated teaching hospital in Toronto, Ontario, Canada. PATIENTS: Inpatients with at least one culture yielding MRSA between April 1996 and March 1998. RESULTS: A total of 20 patients with MRSA infections and 79 colonized patients (with 94 admissions) were identified. This represented a rate of 2.9 MRSA cases per 1,000 admissions. The mean number of additional hospital days attributable to MRSA infection was 14, with 11 admissions having at least 1 attributable day. The total attributable cost to treat MRSA infections was $287,200, or $14,360 per patient The cost for isolation and management of colonized patients was $128,095, or $1,363 per admission. Costs for MRSA screening in the hospital were $109,813. Assuming an infection rate of 10% to 20%, we determined the costs associated with MRSA in Canadian hospitals to be $42 million to $59 million annually. CONCLUSIONS: These results indicate that there is a substantial economic burden associated with MRSA in Canadian hospitals. These costs will continue to rise if the incidence of MRSA increases further.