Causes of death after hip arthroplasty in primary arthrosis.

The causes of death in 1,018 patients operated on for primary osteoarthrosis with cemented total hip arthroplasty (THA) were compared with those of age- and sex-matched orthopaedic control patients and those of the general population in Finland. The mean follow-up period was 12 years for the THA patients and 11 years for the control patients. During the first 4 years after surgery, the mortality of the THA patients from circulatory diseases was significantly increased compared with that of the orthopaedic control patients; the number of deaths in patients with THA was 34 compared with 17 for orthopaedic control patients, the relative risk being 2.00 (95% confidence interval, 1.13-3.54). During the 10-year period after the surgery, the relative risk of death of the THA patients compared with the orthopaedic control patients was 1.50 for death from circulatory diseases (95% confidence intervals, 1.11-2.00), 0.42 for accidental death (95% confidence interval, 0.55-1.08), 0.74 for death from cancer, and 0.77 for death from other causes. The observed numbers of deaths from circulatory diseases or by accidents for patients with THA during a postoperative time frame of 5 to 23 years did not differ from the numbers expected for an age- and sex-matched subgroup of the Finnish population. The number of deaths from cancer was less than expected (P = .046).

Complications, comorbidities, and mortality: improving classification and prediction.

OBJECTIVE: First, to compare the distribution of complications and comorbidities associated with 17 common surgical procedures. We then describe the effect of augmenting an ICD-9-CM version of the Charlson comorbidity index, given the possible confounding of comorbidities and complications, for three common inpatient surgical procedures: coronary artery bypass surgery, pacemaker surgery, and hip fracture repair. DATA SOURCES AND STUDY SETTING: Individuals having one of the above procedures between April 1, 1990 and March 31, 1994, identified from Manitoba Health hospital discharge data, and their extracted records. STUDY DESIGN: Design was cross-sectional and longitudinal using Manitoba data on hospital utilization and mortality. DATA COLLECTION/EXTRACTION: Manitoba hospital discharge abstracts permit identifying whether or not the diagnosis represents an in-hospital complication of care. Two data sets were created for each procedure, one including complication diagnoses and another with complications removed. PRINCIPAL FINDINGS: The degree to which complications contaminated estimation of comorbidity depended both on the procedures studied and on the covariates selected. The unique structure of the algorithm for the Charlson comorbidity index led to complication diagnoses having only a minor effect on the comorbidity score generated. Unless a data set affords the opportunity to remove complication diagnoses, the improvement in comorbidity detection afforded by augmenting the Charlson index, combined with the potential for overestimation of comorbidity, seem sufficiently modest to contraindicate such augmentation.

Relationship between mortality rates and hospital patient volume for Medicare patients undergoing major orthopaedic surgery of the hip, knee, spine, and femur.

This study examines the relationship between mortality rates and hospital patient volume for major orthopaedic surgery. All Medicare patients from fiscal years 1993 and 1994 in diagnosis-related groups (DRGs) 209, 210, and 214 were included, covering hip and knee arthroplasty, other hip and femur procedures, and spine procedures. Within DRG 209, five procedures were studied in more detail: total hip arthroplasty, partial hip arthroplasty, revision total hip arthroplasty, total knee arthroplasty, and revision total knee arthroplasty. Higher-volume hospitals had lower mortality rates, both in-house and in-house plus 30-day, for each of the DRGs studied and for each of the individual procedures within DRG 209. Age and sex were examined as potential causes of the differences in mortality rates, but no attempt was made to adjust for comorbidities or orthopaedic degree of difficulty. Results for 1995 are included in an appendix.

Stanmore total hip replacement in younger patients: review of a group of patients under 50 years of age at operation.

Fifty-seven Stanmore Total Hip replacements were implanted between 1974 and 1986 in patients under the age of 50 years. We have reviewed the results in terms of survivorship and function, and assessed the reasons for revision. Of the original 57, 22 (39%) have been revised at an average of 12 years from implantation, usually for aseptic loosening. Most of them had originally been implanted for osteoarthritis. Prostheses cemented with second-generation techniques have lasted significantly longer, and acetabular loosening emerged as a continuing problem. The overall survivorship was 90% at 10 years and 68% at 15 years. Cemented hip replacement appears to be a viable option in younger patients and the Stanmore implant is comparable with other cemented prostheses in this age group.

Loss to follow-up matters.

Survival analysis of joint replacement relies on the assumption that surgical procedures in patients lost to follow-up have the same chance of failing as those in patients who continue to be assessed. Our study questions that assumption. During the 16-year follow-up of 2268 patients who had received total hip replacements 142 (6%) were lost to follow-up. The cumulative loss at 15 years was 20%. At their last assessment, patients who subsequently failed to attend for follow-up had significantly worse pain, range of movement and opinion of their progress (p < 0.001) and significantly worse radiological features than a matched control group (p < 0.01). Patients lost to follow-up have a worse outcome than those who continue to be assessed. Consequently, a survival analysis that does not take into account such patients is likely to give falsely optimistic results. It is therefore essential that vigorous attempts are made to minimise loss to follow-up, and that the rate of such loss is quoted. The overall loss to follow-up disguises the magnitude of the problem, which is best quantified by a cumulative rate of follow-up. The reliability of a study can be assessed by a loss-to-follow-up quotient, calculated by the number of failures: the lower the quotient the more reliable the data. Ideally, the quotient should be less than 1.

The total cost of hip-joint replacement; a model for purchasers.

A computer-based model is used to investigate the total cost of primary total hip-joint replacement. The model takes into account the probability of prosthesis failure, death and re-revision. The results emphasize the importance of age at insertion, demonstrating that the expected life-span of the patient has a major influence on the total cost for a given prosthesis. The discussion considers the idea of a 'lifetime care package' to encapsulate the concept of quality when considering the purchasing of total hip replacements. If it is assumed that a primary replacement episode costs 3500 pounds and revision surgery costs twice as much, then the additional premium on the best implant currently available would be 630 pounds. The premium payable on the same patient using the worst design would be 3080 pounds. This difference reflects the importance of quality in total hip replacement surgery.

Early post-operative mortality following primary total hip replacement.

A study was undertaken to determine the excess risk of death following primary total hip replacement (THR). All patients who underwent THR or were placed on the waiting list for THR during an 18-month period were studied as to their mortality. The dates of all deaths among both of these populations, and age- and sex-specific mortality rates for the Scottish population, were obtained from the Registrar General for Scotland. It was possible to determine a mortality rate for those patients operated upon and those patients who waited 1 year for their operation. The crude mortality rate, standardized mortality ratio (SMR) and excess risk of death were calculated for the patients operated upon. The crude mortality rate was 1.8% and the SMR was 45.5 for the operated-upon group. The excess risk of death associated with THR within the first 3 post-operative months was calculated in two ways. The relative mortality ratio was determined to be 2.37, and the comparative mortality ratio was calculated to be 1.6 for the operated-upon population. Patients selected for THR are in general fitter than average, and the excess risk of death in the first 3 post-operative months after THR is of the order of 1.6.

Unipolar or bipolar prosthesis for displaced intracapsular hip fracture in octogenarians: a randomised prospective study.

We performed a randomised prospective trial to compare a cemented unipolar prosthesis (Thompson) with a cemented bipolar prosthesis (Monk) in the treatment of displaced intracapsular fractures of the hip in patients over 80 years of age. Patients with a mental test score of less than 5/13 were excluded but the mortality was still about 30% at one year in both groups. We therefore feel that subjective criteria such as the level of pain and the return to the preinjury state are of paramount importance. Two years after operation there was no statistical difference between the rate of complications in the two groups. After adjusting for confounding factors such as differences in the level of function before injury between the groups, the degree of return to the preinjury state was significantly greater (p = 0.04) when using the unipolar prosthesis, which is one-quarter of the price of the bipolar. We cannot therefore justify the use of an expensive bipolar prosthesis in patients over 80 years of age.

Health status before and mortality after hip fracture.

A cohort study was done to determine the direct impact of hip fracture on mortality in older people. Survival was compared between 211 hip fracture patients from a defined area and 201 non-hip fracture control subjects randomly selected from the same area. The mortality rate 1 year after hip fracture was 21.7%; 1-year mortality in the comparison group was 4.7%. The crude hazard ratio for hip fracture and mortality was 4.0 (95% confidence interval [CI] = 2.2, 7.4); adjusting for multiple health-related variables reduced it to 3.3 (95% CI = 1.7, 6.5). This finding suggests that the observed excess mortality after hip fracture is not explained by poor prefracture health status.

Cemented total hip arthroplasty in patients with osteonecrosis. A 6-year minimum follow-up study of second-generation cement techniques.

Twenty patients with osteonecrosis of the femoral head underwent 28 total hip arthroplasties using cement from 1981 to 1985. Femoral reconstruction was by use of second-generation cement techniques. Twenty-four hips in 17 patients were available for review at a mean follow-up period of 7.7 years. The mean age at surgery was 55 years. Clinical evaluation demonstrated 79% excellent, 4% good, and 4% fair results. Three hips (12.5%) required revision for loosening. The cumulative probability of survival was estimated to be 85.7% at 10 years. Second-generation cement techniques and implant designs did improve the clinical results in this high-risk group; however, the overall mechanical failure rate remained high.

Assessment of HCFA's 1992 Medicare hospital information report of mortality following admission for hip arthroplasty.

OBJECTIVE: The Health Care Financing Administration (HCFA) produced annually from 1987 through 1994 mortality data information as part of the Medicare Hospital Information Project (MHIP) report. We assessed the validity of these data for hip arthroplasty for one state Medicare population and we analyzed the accuracy of the predictions derived from the Bailey-Makeham mortality model for this procedure. DATA SOURCES AND STUDY SETTING: The study sample consisted of claims and model data from 1,421 Medicare patients who underwent hip arthroplasty at acute care Arkansas hospitals from October 1990 through September 1991. STUDY DESIGN: Patients were stratified into two groups based on reason for surgery (fracture status): reconstruction or fracture management. Patient survival experience was compared between the two groups. The effect of fracture status on the HCFA model's predictive ability was examined empirically and via a simulation study. RESULTS: Our results indicate that hip arthroplasty patients are not uniform with regard to outcome, depending on the reason for the surgery. Patients with fracture had a much higher 30-day mortality rate than those who underwent reconstruction (p < .001). The empirical data and the simulation study suggest that the Bailey-Makeham model underestimates mortality for reconstructive surgery in fracture patients, providing a false benchmark for those institutions that perform hip arthroplasty on predominantly one category of patients. CONCLUSION: Published HCFA data concerning mortality for hip arthroplasty combines two different patient populations into one statistic. Casual examination of these data could result in a false benchmark for analysis of institutional performance. An important implication from this study for policymakers who base decisions on "report cards" or performance measurement reports is that, although they are necessary,generic case-mix, comorbidity, and severity of illness adjustments may not be sufficient to achieve accurate representations of outcomes, and that more disease/procedure--specific adjustments may be needed to avoid inappropriate conclusions.

A cost-effectiveness analysis of total hip arthroplasty for osteoarthritis of the hip.

OBJECTIVE: To quantify the trade-off between the expected increased short- and long-term costs and the expected increase in quality-adjusted life expectancy (QALE) associated with total hip arthroplasty (THA) for persons with functionally significant hip osteoarthritis. DESIGN: A cost-effectiveness study was performed from the societal perspective by constructing stochastic tree, decision analytic models designed to estimate lifetime functional outcomes and costs of THA and nonoperative managements. MAIN OUTCOME MEASURES: A modified four-state American College of Rheumatology functional status classification was used to measure effectiveness. These functional classes were assigned utility values to allow the relative effectiveness of THA to be expressed in quality-adjusted life years (QALYs). Lifetime costs included costs associated with primary and potential revision surgeries and long-term care costs associated with the functionally dependent class. DATA USED IN THE COST-EFFECTIVENESS MODEL: Probability and incidence rate data were summarized from the literature. The THA hospital cost data were obtained from local teaching hospitals' cost accounting systems. Estimates of recurring medical costs for functionally significant hip osteoarthritis and for custodial care were derived from the literature. RESULTS: The THA cost-effectiveness ratio increases with age and is higher for men than for women. In the base-case scenario for 60-year-old white women who have functionally significant but not dependent hip osteoarthritis, the model predicts that THA is cost saving because of the high costs of custodial care associated with dependency due to worsening hip osteoarthritis and that the procedure increases QALE by about 6.9 years. In the base-case scenario for men aged 85 years and older, the average lifetime cost associated with THA is $9100 more than nonoperative management, with an average increase in QALE of about 2 years. Thus, the THA cost-effectiveness ratio for men aged 85 years and older is $4600 per QALY gained, less than that of procedures intended to extend life such as coronary artery bypass surgery or renal dialysis. Worst-case analysis suggests that THA remains minimally cost-effective for this oldest age category ($80,000/QALY) even if probabilities, rates, utilities, costs, and the discount rate are simultaneously varied to extreme values that bias the analysis against surgery. CONCLUSIONS: For persons with hip osteoarthritis associated with significant functional limitation, THA can be cost saving or, at worst, cost- effective in improving QALE when both short- and long-term outcomes are considered. Further research is needed to determine whether this procedure is actually being used in this cost-effective manner, especially in older age categories.

Appropriateness of total hip replacement in the United Kingdom.

The paper discusses the use of consensus models in determining the application of Total Hip Replacement surgery. The paper notes the wide national and international variation in use of this procedure but considers it in the broader context of reaching consensus on other surgical interventions.

Health care report cards. Validity of case definitions.

Administrative databases are increasingly being used to construct health care report cards. We analyzed information from one of the original report cards, the Medicare Hospital Information Project. Assessment of mortality statistics for three clinical entities--coronary artery bypass surgery, hip reconstruction, and treatment of sepsis--demonstrated widespread outcome variances that reflected imperfect definitions rather than performance issues in clinical care. The use of administrative data sets to design report cards requires clinical expertise to ensure validity of the data. Designers of report card measures should share preliminary data with providers to enable feedback in methods and uncover definitional and validity concerns before widespread dissemination.

[Total hip alloplasty using the Müller method. A six and a half year follow-up study]. / Total hoftealloplastik a.m. Müller. En seks et halvt års efterundersøgelse.

From January 1984 to December 1986, 383 total hip arthroplasties were performed in 353 patients. Median age at operation was 69 (24-85) years. At follow-up median 78 (62-102) months after operation, 261 patients with 278 arthroplasties were still alive. A questionnaire was sent to all living patients, 258 patients (99 per cent) replied. Fifty-seven patients with 61 arthroplasties complained of pain and were called in for a check-up including x-ray. Including the dead patients a total of six arthroplasties had been revised, two because of aseptic loosening of the cup and three because of loosening of both components. One had been revised because of deep infection. In the patients called in for check-up seven were suspected of loosening of the stem and one of loosening of the cup. Survival analysis according to Kaplan-Meier showed a survival rate of the prosthesis of 98.5 per cent at 61/2 years. It is concluded that the results after total hip arthroplasties with the straight stem Müller prosthesis are satisfactory. The patients from this study will be followed prospectively from now on to investigate the long-term survival of this type of prosthesis.

Cemented revision of failed total hip arthroplasty. Survivorship analysis.

A review of 107 total hip arthroplasties performed with acrylic cement in 89 patients at Columbia-Presbyterian Medical Center by 1 surgeon from 1971 to 1990 revealed a clinical survivorship of 97% at 5 years and 76% at 10 years. The average followup was 7.7 years. Analysis of radiographs revealed a 94% success rate at 5 years and 62% at 10 years. A transtrochanteric approach was used in 99% of procedures. The 13 definite failures (12.1%) included 8 rerevisions (7.5%) and 5 failures (4.6%) pending revision. Modified Merle d'Aubigné and Postel postoperative scores increased significantly from preoperative values (pain, 2.8-5.3 points; movement, 3.2-5.2 points; function, 2.6-5.4 points). Bone grafting was required in 33% of procedures and did not affect survivorship: 24% of procedures required acetabular bone grafts; 4% femoral bone grafts; and 5% acetabular and femoral grafts. In 46% of hips, removal of the original well-fixed femoral cement and plug was deliberately incomplete. Stems of standard length were used for these partially rechannelized femurs because the old distal cement column served as a plug for the canal. Old osseointegrated polymethylmethacrylate was left behind to bond with the new cement column. Cement fracture, complete demarcation, and young age were negatively correlated with survivorship.

Evaluation of new technologies for total hip replacement. Economic modelling and clinical trials.

Cost is a factor in the choice of prosthetic components in joint replacement. For a given performance, the least expensive components are the most cost-effective. When evaluating a new prosthesis with an unknown outcome, the use of an economic model allows estimation of potential cost-effectiveness. We used published data for the survival of cemented total hip replacements from Sweden, and cost and demographic information from New South Wales, Australia, in such a model. In young active total hip recipients a new prosthetic design which offered a 90% improvement in survivorship over 15 years and a 15% reduction in the cost of revision surgery, could be sold at a price of 2 to 2.5 times that of conventional cemented components such as the Charnley Low Friction Arthroplasty and still be cost-effective. Using more likely estimates of the improved performance of new technology, however, the upper limit of cost-effectiveness is an increase of 1.5 to 1. Only a very small increase in the cost of a prosthesis could ever be justified for older patients of either sex. Most of the potential benefits of a better level of survivorship appear towards the end of the 15-year period. The results of modelling may be incorporated in clinical trial design. Given the known performance of some well-established and relatively inexpensive designs of prostheses, very large randomised studies would be required to prove an improvement in performance.

Hip arthroplasty in hemophilic arthropathy.

As hemophilic arthropathy infrequently affects the hip joint, we performed a multicenter retrospective study to determine the results of hip arthroplasty in hemophilic patients. Thirty-four hip arthroplasties were performed in twenty-seven male patients at four major hemophilia centers from October 1972 through September 1990. Twenty-six patients had classic hemophilia and one had factor-IX deficiency. The mean age of the patients at the time of the operation was thirty-eight years (range, fifteen to seventy-three years). The mean duration of follow-up was eight years, with a minimum of two years for all patients who were still alive at the time of this review. Four patients were seropositive for the human immunodeficiency virus at the time of the operation, and sixteen patients were seropositive at the time of the most recent follow-up examination. Nine patients (33 per cent) died before the time of this review; seven had been seropositive for the human immunodeficiency virus. There were twenty-six total hip arthroplasties performed with cement, six total hip arthroplasties performed without cement, one total hip arthroplasty in which the femoral component was inserted with cement and the acetabular component was inserted without it (so-called hybrid arthroplasty), and one bipolar arthroplasty performed with cement. There were no early infections after these thirty-four primary arthroplasties. There were three late infections around prostheses inserted with cement, and all led to a resection arthroplasty. Six (21 per cent) of the twenty-eight cemented femoral components and six (23 per cent) of the twenty-six cemented acetabular components were revised because of aseptic loosening.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship of surgical volume to short-term mortality, morbidity, and hospital charges in arthroplasty.

In 1992, the Agency of Health Care Administration in Tallahassee, Florida, started releasing, as part of the patient discharge information, the names of the treating physicians, in addition to demographic and diagnostic data. This information is available to the general public for a small price and is being used by health planners, hospital administrators, finance departments, third-party payers, and other agencies involved in health care. Patient discharge information was used to assess the effects of volume on the short-term outcome of primary and revision hip and knee arthroplasty as a function of surgeon and hospital in the State of Florida, during 1992. A total of 19,925 primary and 2,536 revision arthroplasties of the hip and knee were performed during 1992 in Florida and were available for study. After the doctors and hospitals were arbitrarily divided into three case volume groups (low, medium, high), results showed that in primary arthroplasty, surgeons with a low volume of primary cases (< 10) have a significantly higher mortality rate (24%), higher average charges ($25,000), and increased average length of hospital stay (9.3 days). In revision surgery, physicians with a low volume of cases (< 10) have a higher mortality rate (13%) and increased average length of hospital stay (9.8 days). Patients discharge information has many potential uses for investigators interested in the short-term outcome of arthroplasty. In their present form, these databases should not be released to the general public or the media. Lastly, the volume-outcome relation for a specific surgical procedure should, in addition to case severity, account for characteristics affecting the degree of technical difficulty.