Robert Poss

Derivation and Prospective Validation of a Simple Index for Prediction of Cardiac Risk of Major Noncardiac Surgery

BACKGROUND Cardiac complications are important causes of morbidity after noncardiac surgery. The purpose of this prospective cohort study was to develop and validate an index for risk of cardiac complications. METHODS AND RESULTS We studied 4315 patients aged > or = 50 years undergoing elective major noncardiac procedures in a tertiary-care teaching hospital. The main outcome measures were major cardiac complications. Major cardiac complications occurred in 56 (2%) of 2893 patients assigned to the derivation cohort. Six independent predictors of complications were identified and included in a Revised Cardiac Risk Index: high-risk type of surgery, history of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, preoperative treatment with insulin, and preoperative serum creatinine >2.0 mg/dL. Rates of major cardiac complication with 0, 1, 2, or > or = 3 of these factors were 0.5%, 1.3%, 4%, and 9%, respectively, in the derivation cohort and 0.4%, 0.9%, 7%, and 11%, respectively, among 1422 patients in the validation cohort. Receiver operating characteristic curve analysis in the validation cohort indicated that the diagnostic performance of the Revised Cardiac Risk Index was superior to other published risk-prediction indexes. CONCLUSIONS In stable patients undergoing nonurgent major noncardiac surgery, this index can identify patients at higher risk for complications. This index may be useful for identification of candidates for further risk stratification with noninvasive technologies or other management strategies, as well as low-risk patients in whom additional evaluation is unlikely to be helpful.

Rates and Outcomes of Primary and Revision Total Hip Replacement in the United States Medicare Population

Background: Information on the epidemiology of primary total hip replacement is limited, and we are not aware of any reports on the epidemiology of revision total hip replacement. The objective of this study was to characterize the rates and immediate postoperative outcomes of primary and revision total hip replacement in persons sixty-five years of age and older residing in the United States.Methods: We used Medicare claims submitted by hospitals, physicians, and outpatient facilities between July 1, 1995, and June 30, 1996, to identify individuals who had undergone elective primary total hip replacement for a reason other than a fracture (61,568 patients) or had had revision total hip replacement (13,483 patients). Annual incidence rates of primary and revision total hip replacement were calculated, and multivariate modeling was used to evaluate the association between patient characteristics and surgical rates. The rates of occurrence of five complications within ninety days postoperatively were also evaluated, and relationships between those outcomes and patient characteristics were assessed with use of multivariate models adjusted for hospital and surgeon volume.Results: The rates of primary total hip replacement were three to six times higher than the rates of revision total hip replacement. Women had higher rates than men, and whites had higher rates than blacks. The rates of primary and revision total hip replacement increased with age until the age of seventy-five to seventy-nine years and then declined. The rates of complications occurring within ninety days after primary total hip replacement were 1.0% for mortality, 0.9% for pulmonary embolus, 0.2% for wound infection, 4.6% for hospital readmission, and 3.1% for hip dislocation. The rates after revision total hip replacement were 2.6%, 0.8%, 0.95%, 10.0%, and 8.4%, respectively. Factors associated with an increased risk of an adverse outcome included increased age, gender (men were at higher risk than women), race (blacks were at higher risk than whites), a medical comorbidity, and a low income.Conclusions: Analysis of United States Medicare population data showed that the rates of total hip replacement increased with age up to the age of seventy-five to seventy-nine years and that blacks had a significantly lower rate of total hip replacement than whites. The overall rates of adverse outcomes were relatively low, but they were significantly higher after revision than after primary total hip replacement.Level of Evidence: Prognostic study, Level II-1 (retrospective study). See p. 2 for complete description of levels of evidence.

Association Between Hospital and Surgeon Procedure Volume and Outcomes of Total Hip Replacement in the United States Medicare Population

Background: The mortality and complication rates of many surgical procedures are inversely related to hospital procedure volume. The objective of this study was to determine whether the volumes of primary and revision total hip replacements performed at hospitals and by surgeons are associated with rates of mortality and complications. Methods: We analyzed claims data of Medicare recipients who underwent elective primary total hip replacement (58,521 procedures) or revision total hip replacement (12,956 procedures) between July 1995 and June 1996. We assessed the relationship between surgeon and hospital procedure volume and mortality, dislocation, deep infection, and pulmonary embolus in the first ninety days postoperatively. Analyses were adjusted for age, gender, arthritis diagnosis, comorbid conditions, and income. Analyses of hospital volume were adjusted for surgeon volume, and analyses of surgeon volume were adjusted for hospital volume. Results: Twelve percent of all primary total hip replacements and 49% of all revisions were performed in centers in which ten or fewer of these procedures were carried out in the Medicare population annually. In addition, 52% of the primary total hip replacements and 77% of the revisions were performed by surgeons who carried out ten or fewer of these procedures annually. Patients treated with primary total hip replacement in hospitals in which more than 100 of the procedures were performed per year had a lower risk of death than those treated with primary replacement in hospitals in which ten or fewer procedures were performed per year (mortality rate, 0.7% compared with 1.3%; adjusted odds ratio, 0.58; 95% confidence interval, 0.38, 0.89). Patients treated with primary total hip replacement by surgeons who performed more than fifty of those procedures in Medicare beneficiaries per year had a lower risk of dislocation than those who were treated by surgeons who performed five or fewer of the procedures per year (dislocation rate, 1.5% compared with 4.2%; adjusted odds ratio, 0.49; 95% confidence interval, 0.34, 0.69). Patients who had revision total hip replacement done by surgeons who performed more than ten such procedures per year had a lower rate of mortality than patients who were treated by surgeons who performed three or fewer of the procedures per year (mortality rate, 1.5% compared with 3.1%; adjusted odds ratio, 0.65; 95% confidence interval, 0.44, 0.96). Conclusions: Patients treated at hospitals and by surgeons with higher annual caseloads of primary and revision total hip replacement had lower rates of mortality and of selected complications. These analyses of Medicare claims are limited by a lack of key clinical information such as operative details and preoperative functional status.

Incidence rates of dislocation, pulmonary embolism, and deep infection during the first six months after elective total hip replacement.

Background: The lengths of acute hospital stays following total hip replacement have diminished substantially in recent years. As a result, a greater proportion of complications occurs following discharge. Data on the incidence trends of major complications of total hip replacement would facilitate recognition and management of these adverse events.Methods: We used Medicare claims data on beneficiaries sixty-five years and older who had had elective, primary total hip replacement for a reason other than a fracture (58,521 patients) or had had revision total hip replacement (12,956 patients) between July 1, 1995, and June 30, 1996. We calculated incidence rates of dislocation, pulmonary embolism, and deep hip infection per 10,000 person-weeks for four time-periods following the admission for the surgery (during the index hospitalization, from discharge to four weeks postoperatively, from five to thirteen weeks postoperatively, and from fourteen to twenty-six weeks postoperatively). We then used life-table methods to estimate the cumulative incidence of each complication over the first six postoperative months.Results: Of the patients who had had a primary total hip replacement, 3.9% had a dislocation, 0.9% had a pulmonary embolism, and 0.2% had a deep infection in the first twenty-six postoperative weeks. In the revision total hip replacement cohort, the proportions with dislocation, pulmonary embolism, and deep infection were 14.4%, 0.8%, and 1.1%, respectively. The rates of these adverse outcomes were highest during the index hospitalization, diminished considerably in the period from discharge to four weeks postoperatively, and continued to drop in the periods from five to thirteen and fourteen to twenty-six weeks postoperatively.Conclusions: The incidence rates of dislocation, pulmonary embolism, and deep infection are highest immediately after total hip replacement, but they continue to be elevated throughout the first three postoperative months. With the lengths of hospital stays continuing to diminish, an increasing proportion of complications will occur in outpatients. These findings provide a basis for developing strategies to prevent these complications in the postdischarge management of patients who have had elective total hip replacement.Level of Evidence: Prognostic study, Level II-1 (retrospective study). See p. 2 for complete description of levels of evidence.

Long-term complications after total knee arthroplasty with or without resurfacing of the patella.

The long-term complications related to the patella were retrospectively evaluated for 891 knees (684 patients) that had had a total arthroplasty, with or without resurfacing of the patella, with use of an unconstrained, condylar, posterior-cruciate-preserving prosthesis. The study population comprised two groups of patients who were similar in size, age, sex distribution, and diagnosis. One group (396 knees [303 patients]) had had a total knee arthroplasty with patellar resurfacing and the other group (495 knees [381 patients]) had had the same procedure without resurfacing. The average duration of follow-up was six and one-half years (range, two to fifteen years). The decision to resurface the patella was based on subjective inspection of the articular surface and on assessment of patellar tracking at the time of the operation. Resurfacing was performed if there was loss of cartilage, exposed bone, gross surface irregularities, or tracking abnormalities. Complications occurred an average of three years (range, immediately postoperatively to nine years) after the operation in the group that had had resurfacing and an average of four years (range, immediately post-operatively to ten years) postoperatively in the group that had not had resurfacing. In the group that had had resurfacing, there was loosening of the patellar component in five knees, patellar subluxation in four knees, fracture of the patella in three knees, rupture of the patellar tendon in three knees, and chronic peripatellar pain in one knee. In the group that had not had resurfacing, the complications included patellar subluxation in five knees, rupture of the patellar tendon in two knees, and chronic peripatellar pain in fifty-one knees.(ABSTRACT TRUNCATED AT 250 WORDS)

Posterior Approach to Total Hip Replacement Using Enhanced Posterior Soft Tissue Repair

The two senior authors (PMP, RP) independently began using an identical enhanced posterior soft tissue repair after total hip replacement through a posterior approach. In the first authors experience, a dislocation rate of 4% in 395 patients before using the enhanced closure was reduced to 0% in 395 patients in whom the enhanced closure was performed. In the second authors experience, 160 total hip replacements had a dislocation rate of 6.2% before the enhanced closure whereas 124 total hip replacements had a dislocation rate of 0.8% after the enhanced closure. These results are highly statistically significant.

Dislocation in total hip arthroplasties.

In a series of 1,443 total hip arthroplasties performed between 1970 and 1975, dislocation was the most frequent complication and its incidence was found to be increasing. Dislocatin was frequently associated with component malposition that the surgeon was not aware of at the time of surgery and was relatively frequent among less experienced surgeons. It was especially frequent if the patient had had previous hip surgery and was related to the difficulty of the surgery rather than the primary hip disease. Increasing incidence was associated with change in operative technique and less stringent patient selection. Dislocation was 2 1/2 times more frequent if trochanteric osteotomy was not performed. The tip of the greater trochanter was moved significantly closer to the center of the prosthetic head in the patients who dislocated. Traction for up to three weeks did not lower the incidence of subsequent dislocation compared with mobilization of the patients as soon as tolerated after dislocation. Surgery was effective in preventing further dislocations in patients with recurrent dislocation and component malposition. The use of an articulated prosthesis is not recommended.

Factors influencing the incidence and outcome of infection following total joint arthroplasty.

During a ten-year period, 4240 total hip, knee, and elbow arthroplasties were performed. The overall infection rate was 1.25%. Certain groups were identified as being at higher risk of infection following total joint arthroplasty: rheumatoid arthritics were at 2.6 times greater risk than osteoarthritics; patients undergoing total hip arthroplasty as a revision of a previous operation were eight times more likely to have infection than those undergoing a primary operation; and patients with metal-to-metal hinged knee prostheses, when compared with patients with metal-to-plastic knee prostheses, were 20 times more likely to have infection. The majority of infections could be attributed either to perioperative problems or late bacterial seeding from a distant site. Although most infections occurred by two years after operation, late infections, particularly in rheumatoid patients via the hematogenous route, occurred as long as nine years after operation. There was no correlation between the Grams-staining characteristics of the pathogen and the outcome of the infected joint. Gram-negative organisms were frequent in the perioperative period and reflected either nosocomial infection or the ineffectiveness of the prophylactic antibiotic regimen used in inhibiting gram-negative pathogens. The major factors that influenced the outcome of the infected joint included the interval from the initial surgery to recognition of infection, the delay in institution of appropriate treatment, the particular joint that was infected, the integrity of the bone-cement interface, the type of prosthesis used, and the host susceptibility. Identification of high-risk groups and the recognition that patients with joint implants are at risk of infection at any time in the postoperative period may lead to a lowered infection rate in the future.

Long-term results of revision total hip replacement. A follow-up report.

The results of 110 revision total hip replacements performed for aseptic failure, with an average follow-up of 3.4 years, were reported in 1982. We were able to continue to follow ninety-nine of these patients for an average of 8.1 years (range, five to 12.5 years). With this longer follow-up, we found that twenty-nine (29 per cent) of these revised arthroplasties have since failed. Most of the failures after 1982 occurred in the hips that were known to have a progressive radiolucency at the time of the first evaluation. We concluded that there is an increased failure rate with longer follow-up of revision total hip replacement, and that progressive radiolucency at an interface indicates a poor prognosis for the arthroplasty.

Health-Related Quality of Life After Elective Surgery

Objective:To examine the responsiveness of the 36-Item Short Form Health Survey (SF-36) to clinical changes in three surgical groups and to study how health-related quality of life (HRQL) changes with time among patients who undergo total hip arthroplasty, thoracic surgery for treatment of non-small-cell lung cancer, or abdominal aortic aneurysm (AAA) repair.Design:Prospective cohort study with serial evaluations of HRQL preoperatively and at 1, 6, and 12 months after surgery.Setting:University tertiary care hospital.Patients:Of 528 patients, more than 50 years of age, who were admitted for these elective procedures, 454 (86%) provided preoperative health status data and are members of the study cohort. At 12 months after surgery, 439 (93%) of the cohort was successfully contacted and 390 (90%) provided follow-up interviews.Measurements and main results:The Medical Outcomes Study SF-36, the Specific Activity Scale, five validated health transition questions, and a 0 to 100 scale measure of global health were used to assess changes in health status at 1, 6, and 12 months after surgery. Change in health status as measured by the SF-36 demonstrated that physical function and role limitations due to physical health problems were worse 1 month after these three surgeries. However, by 6 months after surgery, most patients experienced significant gains in the majority of the dimensions of health, and these gains were sustained at 12 months after surgery. Longitudinal changes in the SF-36 were positively associated with responses to the five health transition questions, to changes on the Specific Activity Scale and global health rating question, and to clinical parameters for persons who had AAA repair. These findings indicate that the SF-36 has evidence of validity and is responsive to expected changes in HRQL after elective surgery for these procedures.Conclusions:For the total hip arthroplasty patients, responsiveness was greatest for the SF-36 scales that measure physical constructs. However, for the two other procedures and at various points of recovery, significant changes were observed for all eight subscales, suggesting that responsiveness was dependent on the type of surgery and the timing of follow-up, and that multidimensional measures are needed to fully capture changes in HRQL after surgery.