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Biomedical subjects

R B Keller

Publications and source records attributed to R B Keller.

At least 37 records · Page 2Linked to original sources
PubMed1997

Prognostic value of a hand symptom diagram in surgery for carpal tunnel syndrome.

OBJECTIVE: To evaluate symptom patterns on a hand diagram as predictors of surgical outcome in carpal tunnel syndrome (CTS). METHODS: 202 patients with CTS enrolled in a prospective, community based cohort study in Maine completed a hand symptom diagram before surgery and at 6 month followup. They were asked to mark on the hand diagram the location of 3 symptoms: pain, numbness/tingling (NT), and "other" symptoms. The diagram was first divided into 6 regions following a standardized procedure. For the 6 regions, symptom patterns were identified separately for each of the 3 symptoms. Outcomes 6 months after surgery were expressed as the percentage of change on the Symptom Severity Scale and Function Status Scale of the Carpal Tunnel Syndrome Assessment Questionnaire, and the satisfaction with the results of the surgery. RESULTS: Several distinct symptom patterns were associated with the 3 principal outcomes in univariate and multivariate analysis. In linear regression models controlling for the baseline severity of symptoms and function, as well as other predictors, the hand symptom pattern variables accounted for 30, 14, and 24%, respectively, of the total explained variance in satisfaction, symptom severity, and functional status. Patients receiving Workers' Compensation (37% of the cohort) had more wrist pain and NT of the arm, and less pain involving the arm and upper palm. This group also had worse outcomes and were less satisfied with surgery. Drawing expansion was associated with a low score on the SF-36 mental health subscale. However, psychological impairment was not associated with a worse outcome. CONCLUSION: Symptom patterns identified preoperatively with a hand symptom diagram help to predict the outcome of carpal tunnel release.

Adult↗
PubMed1996

The Quebec Task Force classification for Spinal Disorders and the severity, treatment, and outcomes of sciatica and lumbar spinal stenosis.

STUDY DESIGN: A prospective cohort study of patients in Maine with sciatica and lumbar spinal stenosis treated surgically and nonsurgically. SUMMARY OF BACKGROUND DATA: In 1987, the Quebec Task Force on Spinal Disorders proposed a diagnostic classification to help make clinical decisions, evaluate quality of care, assess prognosis, and conduct research. OBJECTIVES: To assess the Quebec Task Force classification's ability to stratify patients according to severity and treatment at baseline, and to assess changes over time in health-related quality of life, including symptoms, functional status, and disability. METHODS: Five hundred sixteen patients participating in the Maine Lumbar Spine Study who completed baseline and 1-year follow-up evaluations were classified successfully according to the Quebec Task Force classification. Patient characteristics and treatments were compared across Quebec Task Force classification categories. Changes in health-related quality of life over 1 year were assessed according to Quebec Task Force classification category and type of treatment. RESULTS: Among patients with sciatica (n = 370), higher Quebec Task Force classification categories (from 2, pain radiating to the proximal extremity, to 6, sciatica with evidence of nerve root compression) were associated with increased severity of symptoms at baseline. There was no association between Quebec Task Force classification and baseline functional status. Quebec Task Force classification was associated strongly with the likelihood of receiving surgical treatment (P < or = 0.005). Among patients with sciatica treated nonsurgically, improvement at 1 year in back-specific and generic physical function increased with higher Quebec Task Force classification category (P < or = 0.05). Only a nonsignificant trend was observed for surgically treated patients. Patients with lumbar spinal stenosis (Quebec Task Force classification 7, n = 131) had baseline features and outcomes distinct from patients with sciatica. CONCLUSIONS: For patients with sciatica, the Quebec Task Force classification was highly associated with the severity of symptoms and the probability of subsequent surgical treatment. Nonsurgically treated patients in Quebec Task Force classification categories reflecting nerve root compression had greater improvement than those with pain symptoms alone. Among surgical patients, the Quebec Task Force classification was not associated with outcome. These results provide validation for the classification and its wider adoption. Nonetheless, improved diagnostic classifications are needed to predict outcomes better in patients with sciatica who undergo surgery.

Adolescent↗
PubMed1996

The Maine Lumbar Spine Study, Part I. Background and concepts.

STUDY DESIGN: This paper describes the background and factors that led to the development and implementation of the Maine Lumbar Spine Study, a prospective cohort study of patients undergoing surgical and nonsurgical treatment of herniated lumbar disc with sciatica and symptomatic spinal stenosis. OBJECTIVES: To define the factors leading to the study and the methods of designing and implementing a community-based effectiveness study to evaluate the outcomes of herniated lumbar intervertebral disc and spinal stenosis. SUMMARY OF BACKGROUND DATA: Variations in the utilization of surgery for these conditions and physicians' uncertainty regarding the best way to manage them resulted in support of a community-based study of the effectiveness of treatment alternatives. METHODS: A prospective cohort design was used. Methods of patient enrollment, data collection, management, and analysis are described. An innovative method of ascertaining the representativeness of the enrolled versus nonenrolled patient population is presented. RESULTS: The importance of developing community-based networks of physicians is discussed. CONCLUSIONS: These networks play an important role in analyzing practice pattern variations and in stimulating and participating in effectiveness research. Because effectiveness studies must be conducted at the community level, mechanisms must be developed with which to support and implement these efforts.

Cohort Studies↗
PubMed1996

The Maine Lumbar Spine Study, Part II. 1-year outcomes of surgical and nonsurgical management of sciatica.

STUDY DESIGN: The Maine Lumbar Spine Study is a prospective cohort study of patients recruited from the practices of orthopedic surgeons, neurosurgeons, and occupational medicine physicians throughout Maine. OBJECTIVE: To assess 1-year outcomes of patients with sciatica believed to be due to a herniated lumbar disc treated surgically or nonsurgically. SUMMARY OF BACKGROUND DATA: Lumbar spine surgery rates vary by geographic region and may reflect uncertainty about optimal clinical use. METHODS: Eligible consenting patients participated in a baseline interview performed by study personnel and then were mailed follow-up questionnaires at 3, 6, and 12 months. Clinical data were obtained from a physician questionnaire. Outcomes included patient-reported symptoms of leg and back pain, functional status, disability, quality of life, and satisfaction with care. RESULTS: Five hundred seven patients with sciatica, 275 treated surgically and 232 treated nonsurgically initially, were enrolled. Surgically treated patients, on average, had more severe symptoms and had more severe physical and imaging findings than nonsurgically treated patients at entry. Although few surgically treated patients had mild symptoms and few nonsurgically treated patients had severe symptoms, about half in each treatment group had symptoms that fell into a moderate category. At the 1-year evaluation, improvement in symptoms, functional status, and disability were found in both treatment groups. However, surgically treated patients reported significantly greater improvement. For the predominant symptom, either back or leg pain, 71% of surgically treated and 43% of nonsurgically treated patients reported definite improvement (P < 0.001). This effect was even greater after adjustment for differences between treatment groups at entry (relative odds of definite improvement, 4.3; P < 0.001). For patients with moderate symptoms and abnormal physical examination findings, surgical treatment also resulted in greater improvement than nonsurgical treatment. However, there was little difference in the employment or workers' compensation status of patients treated surgically versus nonsurgically (5% vs. 7% unemployed at 1-year follow-up if employed at entry [P = 0.68]; 46% vs. 55% receiving workers' compensation at 1-year follow-up if receiving it at entry [P = 0.30] for surgical and nonsurgical management, respectively). For patients with mild symptoms, the benefits of surgical and nonsurgical treatment were similar. CONCLUSIONS: Although surgically treated patients were on average more symptomatic at entry, there was substantial overlap in symptoms between surgically treated and nonsurgically treated patients. Surgically treated patients with sciatica reported substantially greater improvement at 1-year follow-up. However, employment and compensation outcomes were similar between the two treatment groups, and surgery appeared to provide little advantage for the subset of patients with mild symptoms. These results should be interpreted cautiously, because surgical treatment was not assigned randomly. Long-term follow-up will determine if these differences persist.

Adolescent↗
PubMed1996

The Maine Lumbar Spine Study, Part III. 1-year outcomes of surgical and nonsurgical management of lumbar spinal stenosis.

STUDY DESIGN: A prospective cohort study of patients with lumbar spinal stenosis recruited from the practices of orthopedic surgeons and neurosurgeons throughout Maine. OBJECTIVE: To assess 1-year outcomes of patients with lumbar spinal stenosis treated surgically or nonsurgically. SUMMARY OF BACKGROUND DATA: No randomized trials and few nonexperimental studies have compared surgical and nonsurgical treatment of patients with lumbar spinal stenosis. The authors' goal was to assess 1-year outcomes of patients with lumbar spinal stenosis treated surgically or nonsurgically. METHODS: Eligible, consenting patients participated in baseline interviews and were then mailed follow-up questionnaires at 3, 6, and 12 months. Clinical data were obtained from a physician questionnaire. Outcomes included patient-reported symptoms of leg and back pain, functional status, disability, and satisfaction with care. RESULTS: One hundred forty-eight patients with lumbar spinal stenosis were enrolled, of whom 81 were treated surgically and 67 treated nonsurgically. On average, patients in the surgical group had more severe imaging findings and symptoms and worse functional status than patients in the nonsurgical group at entry. Few patients with mild symptoms were treated surgically, and few patients with severe symptoms were treated nonsurgically. However, of the patients with moderate symptoms, a similar percent were treated surgically or nonsurgically. One year after study entry, 28% of nonsurgically and 55% of surgically treated patients reported definite improvement in their predominant symptoms (P = 0.003). For patients with moderate symptoms, outcomes for surgically treated patients were also improved compared with those of nonsurgically treated patients. Surgical treatment remained a significant determinant of 1-year outcome, even after adjustment for differences between treatment groups at entry (P = 0.05). The maximal benefit of surgery was observed by the time of the first follow-up evaluation, which was at 3 months. Although few nonsurgically treated patients experienced a worsening of their condition, there was little improvement in symptoms and functional status compared with study entry. CONCLUSIONS: At a 1-year evaluation of patient-reported outcomes, patients with severe lumbar spinal stenosis who were treated surgically had greater improvement than patients treated nonsurgically. Comparisons of outcomes by treatment received must be made cautiously because of differences in baseline characteristics. A determination of whether the outcomes observed persist requires long-term follow-up.

Adult↗
PubMed1996

The association between local diagnostic testing intensity and invasive cardiac procedures.

OBJECTIVE: To determine the extent to which geographic variation in invasive cardiac procedures can be explained by the variable use of diagnostic testing. DESIGN: A population-based cohort study using Medicare Part B data (physician services). SETTING AND SUBJECTS: Procedure data for all Medicare beneficiaries in northern New England. MAIN OUTCOME MEASURES: Twelve coronary angiography service areas were constructed for Medicare beneficiaries in northern New England. Age- and sex-adjusted utilization rates were developed for three procedure categories: total stress test, coronary angiography, and revascularization. Total stress tests were further stratified into nonimaging and imaging procedures (eg, thallium). Tests performed in follow-up to invasive procedures were excluded (eg, stress test following revascularizations). Linear regression was used to assess the relationship between procedure categories. RESULTS: A tight positive relationship was found between total stress test rates and the rates of subsequent coronary angiography (R2=0.61, P<.005). Most of the variance was explained by imaging stress tests (R2=0.50, P<.02). A strong relationship was found between coronary angiography and revascularization (R2=0.82, P<.001). Finally, a clear relationship between total stress tests and subsequent revascularizations was also found (R2=0.55, P<.006). CONCLUSION: The population-based rates of diagnostic testing largely explained the variance associated with subsequent therapeutic interventions. Our results suggest that local testing intensity is an important determinant of the variable use of invasive cardiac procedures.

Cardiovascular Diseases↗
PubMed1996

Application of outcomes research in occupational low back pain: the Maine Lumbar Spine Study.

Outcomes research represents an expansion of traditional clinical research to include issues of cost and quality of care in usual clinical practice, emphasizing outcomes that matter most to patients. In low back disorders, outcomes research has focused on the lack of reliable information to support much of clinical practice and has demonstrated marked variability in the treatment of these common problems. The Maine Lumbar Spine Study represents an example of an outcomes research study to investigate the treatment of patients with sciatica in usual clinical practice. Because low back symptoms are a frequent cause of occupational disability, Workers' Compensation patients were explicitly oversampled. Baseline features were significantly different in those patients who were receiving Workers' Compensation versus those who were not. Efforts to compare outcomes by disability status need to control for these differences. Whereas most Workers' Compensation patients were still receiving disability compensation regardless of treatment at 6 months, patients who were treated surgically were more likely to have come off disability and returned to work than nonsurgically treated patients. Long-term follow-up is necessary to determine whether these differences persist.

Adult↗
PubMed1996

Measuring outcomes.

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Health Status Indicators↗
PubMed1996

Basic epidemiology of fractures of the upper and lower limb among Americans over 65 years of age.

Current knowledge regarding the basic epidemiology of fractures is largely limited to a few fracture sites, notably those of the hip and distal forearm. To clarify the patterns of incidence of limb fractures in the elderly, we used data from a 5% sample of the U.S. Medicare population over age 65 years during the years 1986-1990. We identified incident fractures of the proximal humerus, other parts of the humerus, proximal radius/ ulna, shaft of the radius/ulna, distal radius/ulna, pelvis, hip, other parts of the femur, patella, ankle, and other parts of the tibia/fibula from diagnoses and procedures coded on claims for inpatient services, outpatient facility use, and physician services. We used Poisson regression to investigate the relation between demographic factors and fracture risk at these sites. Fractures at the hip were the most common, accounting for 38% of the fractures identified. The proximal humerus, distal radius/ulna, and ankle also were common fracture sites. A pattern of rapidly rising rates with age was seen for fractures of the pelvis, hip, and other parts of the femur among women. Fractures distal to the elbow or knee, however, had, at most, modest increases in incidence with age over 65 years. For each of the fractures studied, women had higher rates than men of the same race, and whites generally had higher rates than blacks of the same gender. Gender-related differences in risk were larger among whites than among blacks, and racial differences in risk were more marked among women than among men.

Aged↗
PubMed1996

Workers' compensation recipients with carpal tunnel syndrome: the validity of self-reported health measures.

OBJECTIVES: This study compared the reliability, validity, and responsiveness of self-reported measures of health related quality of life in recipients and non-recipients of workers' compensation who have carpal tunnel syndrome. METHODS: Patients with carpal tunnel syndrome complete questionnaires at study enrollment and 6 months later scales measuring symptom severity functional status, and satisfaction were included. The scales internal consistency, validity, and responsiveness were assessed. RESULTS: The internal consistencies for each scale were high (Cronbach's alpha .88 to .96) and virtually identical in recipients and nonrecipients of workers' compensation. The correlations between self-reported and objectively measured grip strength were .32 in recipients and .30 in nonrecipients; these correlations were not influenced by whether workers' compensation recipients were out of work. Correlations between changes in scale scores and three indicators of perceived improvement were higher in recipients (.48 to .69) than in nonrecipients (.19 to .41) CONCLUSIONS: The reliability, validity, and responsiveness of these measures were comparable in nonrecipients and recipients of workers compensation, these data support the use of self-report measures in studies of workers.

Adolescent↗
PubMed1995

Assessing health-related quality of life in patients with sciatica.

STUDY DESIGN: This study analyzed health-related quality-of-life measures and other clinical and questionnaire data obtained from the Maine Lumbar Spine Study, a prospective cohort study of persons with low back problems. OBJECTIVE: For persons with sciatica, back pain-specific and general measures of health-related quality-of-life were compared with regard to internal consistency, construct validity, reproducibility, and responsiveness in detecting small changes over a 3-month period. SUMMARY OF BACKGROUND DATA: Data were collected from 427 participants with sciatica. Baseline in-person interviews were conducted with surgical and medical patients before treatment and by mail at 3 months. METHODS: Health-related quality-of-life measures included symptoms (frequency and bothersomeness of pain and sciatica) functional status and well-being (modified back pain-specific Roland scale and Medical Outcomes Study 36-item Short Form Health Survey (SF-36), and disability (bed rest, work loss, and restricted activity days). RESULTS: Internal consistency of measures was high. Reproducibility was moderate, as expected after a 3-month interval. The SF-36 bodily pain item and the modified Roland measure demonstrated the greatest amount of change and were the most highly associated with self-rated improvement. The specific and generic measures changed in the expected direction, except for general health perceptions, which declined slightly. A high correlation between clinical findings or symptoms and the modified Roland measure, SF-36, and disability days indicated a high degree of construct validity. CONCLUSIONS: These measures performed well in measuring the health-related quality-of-life of patients with sciatica. The modified Roland and the physical dimension of the SF-36 were the measures most responsive to change over time, suggesting their use in prospective evaluation. Disability day measures, although valuable for assessing the societal impact of dysfunction, were less responsive to changes over this short-term follow-up of 3 months.

Adolescent↗
PubMed1995

Partnering with physicians to achieve quality improvement.

BACKGROUND: The Maine Medical Assessment Foundation (MMAF) has successfully involved hundreds of Maine physicians in study groups to analyze data on small-area variation and assess physician decision-making patterns. In 1991 the MMAF model was replicated across a tri-state area (Maine, New Hampshire, Vermont) in an effort called the Outcomes Dissemination Project, which is funded by a five-year grant from the U.S. Agency for Health Care Policy and Research. THE OUTCOMES DISSEMINATION PROJECT: Five specialty study groups, each meeting three times a year, examine local and national utilization data, examine guidelines and research findings, participate in outcomes studies and patient education, and disseminate their findings through specialty society presentations and other feedback efforts. The MMAF study group process is based on the beliefs that medicine is a subculture with a complex set of professional values, beliefs, socialization processes, and norms, and that quality improvement efforts work best when they are nonpunitive and educational. ISSUES IN OBTAINING PHYSICIAN INVOLVEMENT: (1) Physicians are willing to change their practices if they are brought into a culturally appropriate improvement program. (2) Related specialties (for example, internists and family practitioners) can often work together effectively on issues of common interest. (3) Involving respected clinical leaders has helped establish the legitimacy of MMAF methods among physicians. (4) Area- and physician-specific data are not made public, so as to build a sense of confidentiality among participants. CONCLUSIONS: The project continues to function as a powerful education process and serves as a model for replication elsewhere.

Attitude of Health Personnel↗
PubMed1994

Outcome measures for studying patients with low back pain.

There is growing recognition in the treatment of back pain that patient perspectives are essential in judging the results of treatment. Improving the patient's "quality of life" is often the main goal of therapy. Thus, although clinical research in the past has focused on physiologic outcomes, such as range of motion, muscle strength, or neurologic deficits, increasing attention is being given to the rigorous measurement of symptoms, functional status, role function, satisfaction with treatment, and health care costs. In many cases, these so-called "soft" outcomes can be measured with a level of reproducibility similar to more conventional clinical data such as imaging test results. Because symptoms and functional outcomes are sometimes only loosely associated with physiologic phenomena, the former outcomes should be measured directly. Modern questionnaires for measuring patient quality of life combine the expertise of social scientists and clinicians and have demonstrated validity. Furthermore, they have some important advantages over simple ratings of "excellent, good, fair, and poor" outcomes, or work status alone. Several modern instruments for measuring health-related quality of life in patients with low back pain are reviewed briefly, describing their content and length. Wider use of these instruments would help to increase clinician familiarity with their meaning and avoid duplication of effort in questionnaire development.

Health Status Indicators↗
PubMed1994

Strategies for outcome research in spinal disorders. An introduction.

The evaluation of the clinical utility of the clinical diagnostic tests and procedures, what works in spinal disorders, and for whom and how treatment affects a patient's symptoms and function are key questions of outcomes research. This paper describes the advantages and limitations of the main study approaches used. Examples from the spine literature on spinal stenosis are used for illustration.

Female↗
PubMed1994

Outcomes after displaced fractures of the femoral neck. A meta-analysis of one hundred and six published reports.

Methods of meta-analysis, a technique for the combination of data from multiple sources, were applied to analyze 106 reports of the treatment of displaced fractures of the femoral neck. Two years or less after primary internal fixation of a displaced fracture of the femoral neck, a non-union had developed in 33 per cent of the patients and avascular necrosis, in 16 per cent. The rate of performance of a second operation within two years ranged from 20 to 36 per cent after internal fixation and from 6 to 18 per cent after hemiarthroplasty (relative risk, 2.6; 95 per cent confidence interval, 1.4 to 4.6). Conversion to an arthroplasty was the most common reoperation after internal fixation and accounted for about two-thirds of these procedures. The remaining one-third of the reoperations were for removal of the implant or revision of the internal fixation. For the patients who had had a hemiarthroplasty, the most common reoperations were conversion to a total hip replacement, removal or revision of the prosthesis, and débridement of the wound. Although we observed an increase in the rate of mortality at thirty days after primary hemiarthroplasty compared with that after primary internal fixation, the difference was not significant (p = 0.22) and did not persist beyond three months. The absolute difference in perioperative mortality between the two groups was small. An anterior operative approach for arthroplasty consistently was associated with a lower rate of mortality at two months than was a posterior approach. Some reports showed promising results after total hip replacement for displaced fractures of the femoral neck; however, randomized clinical trials are still needed to establish the value of this treatment.

Arthroplasty↗