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Biomedical subjects

S V Williams

Publications and source records attributed to S V Williams.

At least 19 recordsLinked to original sources
PubMed2001

Guidelines for the management of patients with chronic stable angina: treatment.

The dual aims of treating patients with chronic stable angina are 1) to reduce morbidity and mortality and 2) to eliminate angina with minimal adverse effects and allow the patient to return to normal activities. In the absence of contraindications, beta-blockers are recommended as initial therapy. All beta-blockers seem to be equally effective. If the patient has serious contraindications to beta-blockers, unacceptable side effects, or persistent angina, calcium antagonists should be administered. Long-acting dihydropyridine and nondihydropyridine agents are generally as effective as beta-blockers in relieving angina. Long-acting nitrates are considered third-line therapy because a nitrate-free interval is required to avoid developing tolerance. All long-acting nitrates seem to be equally effective. Patients with angina should take 75 to 325 mg of aspirin daily unless they have contraindications. Such risk factors as smoking, elevated low-density lipoprotein cholesterol level, diabetes, and hypertension should be treated appropriately. Coronary revascularization has not been shown to improve survival for most patients with chronic angina but may be required to control symptoms. However, coronary artery bypass grafting (CABG) is often indicated for symptomatic patients with left-main disease, three-vessel disease, or two-vessel disease including proximal stenosis of the left anterior descending coronary artery; it improves their survival. Percutaneous transluminal coronary angioplasty is an alternative to CABG for patients with normal left ventricular function and favorable angiographic features. Coronary artery bypass grafting is initially more effective in relieving angina than medical therapy, but the two procedures yield similar results after 5 to 10 years. Eighty percent of patients who undergo CABG remain angina-free 5 years after surgery. In low-risk patients, percutaneous transluminal coronary angioplasty seems to control angina better than medical therapy, but recurrent angina and repeated procedures are more likely than with CABG. Patient education is an important component of management. Long-term follow-up should be individualized to ascertain clinical stability at regular intervals and to reassess prognosis when warranted.

Adrenergic beta-Antagonists↗
PubMed2001

Guidelines for the management of patients with chronic stable angina: diagnosis and risk stratification.

Patients with suspected chronic stable angina can be evaluated in three stages. In stage one, the clinician uses information from the history, physical examination, laboratory tests for diabetes and hyperlipidemia, and resting electrocardiography to estimate the patient's probability of coronary artery disease (CAD). In stage two, additional testing for patients with a low probability of CAD focuses on diagnosing noncoronary causes of chest pain. Patients with a high probability of CAD have stress tests to assess their risk from CAD, and patients with an intermediate probability of CAD have stress tests to estimate the probability of CAD and assess their risk from CAD. Most patients with new-onset angina can start stress testing with exercise electrocardiography. The initial stress test should be a stress imaging procedure for patients with rest ST-segment depression greater than 1 mm, complete left bundle-branch block, ventricular paced rhythm, preexcitation syndrome, or previous revascularization with percutaneous coronary angioplasty or coronary artery bypass grafting. Patients who cannot exercise can have an imaging procedure with stress induced by pharmacologic agents. In stage three, patients with a predicted average annual cardiac mortality rate between 1% and 3% should have a stress imaging study or coronary angiography with left ventriculography. Those with a known left ventricular dysfunction should have cardiac catheterization. Patients with CAD who have an estimated annual mortality rate greater than 3% should have cardiac catheterization to determine whether their anatomy is suitable for revascularization. Patients with an estimated annual mortality rate less than 1% can begin to receive medical therapy.

Algorithms↗
PubMed2000

A functional diagnostic complexity index for rehabilitation medicine: measuring the influence of many diagnoses on functional independence and resource use.

OBJECTIVE: To develop an index that weights diagnostic information (International Classification of Diseases, 9th revision, Clinical Modification, or ICD-9-CM codes) by the extent to which it is expected to affect functional status and inpatient rehabilitation length of stay (LOS). DESIGN: Eleven nationally prominent physiatrists assigned ICD-9-CM codes to ordinal categories by expected effect on functional recovery. A resulting functional diagnostic complexity index score was calculated for each patient by combining the ranked values of each ICD-9-CM code in the discharge record. Analyses were stratified across the 20 rehabilitation impairment categories (RICs) of the Functional Independence Measure-Function Related Groups. DATA: Patients (182,254) discharged from 465 inpatient rehabilitation units in larger hospitals and free-standing rehabilitation hospitals in 1995. RESULTS: High degrees of diagnostic complexity were associated with low levels of functional independence at admission within each of 20 RICs (Spearman R = .06 to .25). Depending on RIC, patients in the highest (compared with the lowest) complexity category had up to a 35% increase in rehabilitation LOS after accounting for the primary medical reason for rehabilitation and severity of disabilities at admission. CONCLUSION: This prototype index of medical complexity offers a promising approach for analyzing the cumulative effects of diagnoses on patients' initial functional status and rehabilitation LOS.

Activities of Daily Living↗
PubMed1999

Health maintenance organizations and hospital quality for coronary artery bypass surgery.

This study uses hospital discharge data for 1992-1994 to assess differences between HMO and insured non-HMO patients in California and Florida with regard to the quality of the hospitals used for coronary artery bypass graft (CABG) surgery. The authors found that commercially insured HMO patients in California used higher quality hospitals than commercially insured non-HMO patients, controlling for patient distance to the hospital. In contrast, commercially insured HMO and non-HMO patients in Florida were similarly distributed across hospitals of different quality levels, whereas Medicare HMO patients in Florida used lower quality hospitals than patients in the standard Medicare program. The authors conclude that the association between HMO coverage and hospital quality may differ across geographic areas and patient populations, possibly related to the maturity and structure of managed care markets.

Aged↗
PubMed1998

Diagnostic coding and medical rehabilitation length of stay: their relationship.

OBJECTIVE: To determine if diagnostic information provided in the form of International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes improves rehabilitation length of stay (LOS) prediction when used in combination with the Functional Independence Measure-Function Related Groups (FIM-FRGs) classification system. DESIGN: Various models characterizing diagnostic information using ICD-9-CM codes were created that included individual ICD-9-CM codes and groupings of those codes by organ or etiology involved. Each method was evaluated using linear regression with the natural logarithm of LOS as the dependent variable. Separate validation data sets were held back to quantify the incremental effect of diagnosis when combined with the FIM-FRG classification system. SETTING: Records from 252 rehabilitation facilities and hospital units across the nation. PATIENTS: Analyses were undertaken using 82,646 records from patients discharged in 1992. RESULTS: The addition of ICD-9-CM diagnostic information to the FIM-FRG classification system increased the variance explained by a maximum of 1.9%, from 31.5% to 33.4%. CONCLUSIONS: Refinement of the FIM-FRGs to include ICD-9-CM diagnoses does not appear warranted on the basis of the small increase in the percentage of explained variance in LOS. We believe the lack of improved prediction with the addition of ICD-9-CM codes relates primarily to incomplete coding practices and to the effect of patients' diagnoses being absorbed in variables as already expressed by the FIM-FRG system. Although ICD-9-CM codes, overall, did not greatly improve LOS prediction, they appeared to have some impact in certain impairment categories.

Brain Injuries↗
PubMed1997

Discharge motor FIM-function related groups.

OBJECTIVE: To develop a patient classification system that groups patients achieving similar functional outcome scores by discharge from medical rehabilitation. DESIGN: Patient groups were developed using a recursive partitioning algorithm and clinical input. Results were validated in a separate set of patient records. SETTING: Two hundred fifty-two free-standing rehabilitation hospitals and distinct part units that participate in the Uniform Data System for Medical Rehabilitation. PATIENTS: The 84,492 rehabilitation inpatients discharged in 1992 were grouped into 20 impairment categories. MAIN OUTCOME MEASURE: Discharge score on the motor subscale of the Functional Independence Measure (FIM). RESULTS: In the Discharge Motor FIM-Function Related Groups (DMF-FRGs) system, patients are first classified into one of 20 impairment categories and then into FRGs by their admission motor FIM scores. Some FRGs are also subdivided on the basis of admission cognitive FIM scores and age. The entire system consists of 139 patient groups that explain 63% of the variation in motor FIM discharge scores in the validation data set. Nontraumatic brain injury and joint replacement DMF-FRGs are provided as examples. CONCLUSION: Clinicians can use the DMF-FRGs to identify groups of patients whose motor FIM scores at discharge are below, within, or above nationally established ranges of values for the purpose of outcomes management, guideline development, and quality improvement. The DMF-FRGs can also be considered in the design of an outcome-based payment system for medical rehabilitation.

Activities of Daily Living↗
PubMed1997

What predicts gastroenterologists' and surgeons' diagnosis and management of common bile duct stones?

BACKGROUND: Because the literature suggests numerous indicators of common bile duct stones, we undertook a systematic assessment of physicians' judgments of the clinical utility of eight indicators: patient age, history of jaundice, history of pancreatitis, levels of serum alanine aminotransferase, alkaline phosphatase, amylase, and total bilirubin, and common bile duct diameter on ultrasonography. METHODS: Random samples of 1500 gastroenterologists and 1500 surgeons were sent a survey asking them to indicate the importance of each potential indicator of common bile duct stones, the likelihood of common bile duct stones for each of nine clinical vignettes, and whether they would order a preoperative ERCP. An abbreviated survey was sent to nonrespondents. RESULTS: Although there was substantial variation in the importances assigned to each indicator, the most important indicators were serum total bilirubin and diameter of common bile duct on ultrasound. The best predictors of the decision to order an ERCP were perceived likelihood of stones and specialty. The average threshold for ordering an ERCP was 37%. Respondents did not differ from nonrespondents in the perceived importance of the eight indicators. CONCLUSIONS: The substantial variation among gastroenterologists and surgeons regarding the optimal approach to common bile duct stones has clinical implications. Patients will receive varying recommendations for care, depending on whom they see.

Adult↗
PubMed1997

The relationship between choice of outcome measure and hospital rank in general surgical procedures: implications for quality assessment.

OBJECTIVE: Institutional complication rates are often used to assess hospital quality of care, particularly for conditions and procedures where mortality rates are not useful because deaths are rare. The objective of this study was to assess the correlation among hospital quality assessment rankings based on adjusted mortality, complication and failure-to-rescue rates. DESIGN: This study used a clinically detailed administrative data set to compare severity and case-mix adjusted hospital outcome rankings for three different measures of quality of care: in-hospital death, complication and failure-to-rescue (in-hospital death following a complication). SETTING AND PATIENTS: Analysis of 74,647 patients who underwent general surgical procedures included in the 1991 and 1992 MedisGroups National Comparative Data Base. MEASUREMENTS: Adjusted outcomes of death, complication and failure to rescue based on multivariable logistic regression models. RESULTS: For 142 hospitals, the correlation between hospital rankings based on the death rate and those ranked by the complication rate was only 0.208 (P = 0.013). A similarly low correlation was present between the complication and failure rate rankings, r = -0.090 (P = 0.287). A higher correlation was observed between the death and failure rate rankings, r = 0.90 (P < 0.001). CONCLUSIONS: For general surgical procedures, hospital rank using the complication rate is poorly correlated with rankings using the death or failure rate. Complication rates should be used with great caution and should not be used in isolation when assessing hospital quality of care.

Hospital Mortality↗
PubMed1997

Routine portable chest radiographs in the medical intensive care unit: effects and costs.

OBJECTIVE: To determine the effects and net costs of routine chest radiographs in a medical intensive care unit (ICU). DESIGN: A prospective, cohort study. A survey of experts in critical care and pulmonary diseases was undertaken to assess the effect of routine radiographs on patient management. SETTING: Medical ICU of a university hospital. PATIENTS: Eighty randomly selected patients admitted to a medical ICU. Two hundred fourteen experts were surveyed; 118 (55%)/214 responded. MEASUREMENTS AND MAIN RESULTS: Daily interviews with medical ICU clinicians were conducted to assess the radiographic findings in the routine radiographs and actions taken based on these findings. Experts evaluated the findings, their importance, the actions taken, and the probability of complications if the actions had not been taken at that time. Experts also predicted increases in length of stay associated with these complications. Presence of radiographic findings, changes in management because of the findings, net costs of routine chest radiographs, cost per finding that prompted an action, and expected changes in length of stay resulting from the actions were also assessed. Seventy-two (33%) of 221 routine radiographs (95% confidence interval: 25% to 39%) had findings, of which 44 (61%) were judged important, and 18 (8%, 95% confidence interval: 5% to 12%) prompted actions. Experts predicted that each action averted, on average, 2.1 +/- 1.7 days (SD) in the medical ICU. Mean savings per routine radiograph was $98. Net savings from routine chest radiographs remained after sensitivity analysis for expected change in length of stay, percentage of patients with routine radiographs, and percentage of routine radiographs that produce changes in management. CONCLUSION: The policy of obtaining routine chest radiographs in the medical ICU is effective and results in net savings.

APACHE↗
PubMed1997

Classifying rehabilitation inpatients by expected functional gain.

OBJECTIVES: To create a more suitable payment system for medical rehabilitation, the authors developed a companion classification system to the original functional independence measure-function-related groups (FIM-FRGs), which classify patients having similar lengths of stay in a rehabilitation hospital or inpatient unit. The companion system presented here groups patients according to their gains in functional status during the rehabilitation stay. METHODS: Data from 84,492 patients discharged from 252 rehabilitation facilities in 1992 were provided by the Uniform Data System for Medical Rehabilitation. Classification rules were formed using clinical judgment and a recursive partitioning algorithm. The gain-FRGs system used four predictor variables: (1) diagnosis leading to disability, admission scores on the (2) motor and (3) cognitive subscales of the FIM, and (4) patient age. RESULTS: The gain-FRGs system contained 74 patient groups and explained 21% of the variation in functional gain for patients in a different set of records withheld for validation. CONCLUSIONS: The gain-FRGs system should be considered for prospective payment systems because it gives the provider an incentive to improve patient outcomes, which is missing in a payment system based on FIM-FRGs alone.

Activities of Daily Living↗
PubMed1997

Development of function-related groups version 2.0: a classification system for medical rehabilitation.

OBJECTIVE: To present a new version (2.0) of the Functional Independence Measure-Function Related Group (FIM-FRG) case-mix measure. DATA SOURCE/STUDY SETTING: 85,447 patient discharges from 252 freestanding facilities and hospital units contained in the 1992 Uniform Data System for Medical Rehabilitation. STUDY DESIGN: Patient impairment category, functional status at admission to rehabilitation, and patient age were used to develop groups that were homogeneous with respect to length of stay. Within each impairment category patients were randomly assigned to one data set to create the system (through recursive partitioning) or a second set for validation. Clinical and statistical criteria were used to increase the percentage of patients classified, expand the impairment categories of FIM-FRGs Version 1.1, and evaluate the incremental predictive ability of coexisting medical diagnoses. Predictive stability over time was evaluated using 1990 discharges. PRINCIPAL FINDINGS: In Version 2.0, the percentage of patients classified was increased to 92 percent. Version 2.0 includes two new impairment categories and separate groups for patients admitted to rehabilitation for evaluation only. Coexisting medical diagnoses did not improve LOS prediction. The system explains 31.7 percent of the variance in the logarithm of LOS in the 1992 validation sample, and 31.0 percent in 1990 discharges. CONCLUSIONS: FIM-FRGs Version 2.0 includes more specific impairment categories, classifies a higher percentage of patient discharges, and appears sufficiently stable over time to form the basis of a payment system for inpatient medical rehabilitation.

Aged↗
PubMed1996

Predictors of common bile duct stones prior to cholecystectomy: a meta-analysis.

BACKGROUND: The decision of whether or not to investigate for common bile duct stones before cholecystectomy utilizes clinical, laboratory, and radiologic information (indicators). There is tremendous individual variation among clinicians in the criteria used for making this decision. Our aim was to perform a meta-analysis of published data to estimate the performance characteristics of the most commonly used preoperative indicators of common bile duct stones. METHODS: Using predetermined exclusion criteria, we selected articles from a MEDLINE search and bibliographic review. Weighted averages were used to determine summary sensitivity, specificity, and positive and negative likelihood ratios for each indicator for stones. RESULTS: From 2221 citations identified, 22 studies met inclusion criteria. The 10 indicators examined were reported in a common fashion in three or more articles, and could be assessed preoperatively. Seven exhibited a specificity greater than 90%. Indicators with positive likelihood ratios of 10 or above were cholangitis, preoperative jaundice, and ultrasound evidence of common bile duct stones. Positive likelihood ratios for dilated common bile duct on ultrasound, hyperbilirubinemia, and jaundice ranged from almost 4 to almost 7. Elevated levels of alkaline phosphatase, pancreatitis, cholecystitis, and hyperamylasemia exhibited positive likelihood ratios of less than 3. CONCLUSIONS: This meta-analysis has identified indicators for duct stones and ranked them according to likelihood ratios. These findings can be applied as guidelines for whether to investigate for duct stones before cholecystectomy.

Cholecystectomy↗
PubMed1996

Mortality and complications associated with laparoscopic cholecystectomy. A meta-analysis.

OBJECTIVE: The purpose of this study was to perform a meta-analysis of large laparoscopic cholecystectomy case-series and compare results concerning complications, particularly bile duct injury, to those reported in open cholecystectomy case-series. SUMMARY BACKGROUND DATA: Since the introduction of laparoscopic cholecystectomy in the United States, hundreds of reports about the technique have been published, many including statements about the advantages of laparoscopic cholecystectomy compared with those of open cholecystectomy. There is an unevenness in scope and quality of the studies. Nevertheless, enough data have accumulated from large series to permit analyses of data regarding some of the most important issues. METHODS: Articles identified via a MEDLINE (the National Library of Medicine's computerized database) search were evaluated according to standard criteria. Data regarding the patient sample, study methods, and outcomes of cholecystectomy were abstracted and summarized across studies. RESULTS: Outcomes of laparoscopic cholecystectomy are examined for 78,747 patients reported on in 98 studies and compared with outcomes of open cholecystectomy for 12,973 patients reported on in 28 studies. Laparoscopic cholecystectomy appears to have a higher common bile duct injury rate and a lower mortality rate. Estimated rates of other types of complications after laparoscopic cholecystectomy generally were low. Most conversions followed operative discoveries (e.g., dense adhesions) and were not the result of injury. CONCLUSIONS: There is wide variability in the amount and type of data reported within any single study, and patient populations may not be comparable across studies. Except for a higher common bile duct injury rate, laparoscopic cholecystectomy appears to be at least as safe a procedure as that of open cholecystectomy.

Cholecystectomy, Laparoscopic↗
PubMed1996

Measuring hospital outcomes from a buyer's perspective.

This study reports lessons learned from a project to develop a flexible, generalizable, and valid method for corporate buyers of hospital care that would permit them to use available secondary data to rate the outcomes quality of all hospitals in a local market area. As hospitalization insurance has moved from coverage that applied equally to all licensed hospitals to arrangements which selected a certain preferred hospital or hospitals and rejected others, the need to determine the quality of different hospitals (as well as what they would cost the insurer or buyer) has become apparent. The product of this project was the development and demonstration of a set of rating methods that build on the strengths available in large hospital discharge data bases, such as (but by no means limited to) that of the Pennsylvania Health Care Cost Containment Council (PHC4). These measures, or others developed using these methods, deal with uncertainty in the data--its diagnosis and treatment--in a conceptually valid and practically useful way, illustrate a process that might be used in the general development of quality measures, and provide a useful critique of some other measures.

Commerce↗