Concepts, knowledge, and language in health-care information systems.
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Artificial Intelligence↗
Biomedical subjects
C G Chute
Publications and source records attributed to C G Chute.
An overview of statistical methods for the classification and retrieval of patient events.
Statistical methods that can support text retrieval are becoming an increasing focus of medical informatics activities. We overview our adaptation of existing knowledge sources to create pseudo-documents for concept based latent semantic indexing. Experience demonstrated this tack of limited practical value, since retrieval performance was invariably unsatisfactory. We discovered this was due in part to the introduction of a vocabulary gap between the queries and the cases we sought to retrieve. In part to address this problem, and to avail our large body of humanly coded text as a knowledge source, we developed a least squares fit alternative for the computer assisted indexing and retrieval of biomedical texts. This technique demonstrates equivalent or superior retrieval performance when compared to all other textual retrieval techniques. It does not depend upon elaborate knowledge bases, lexicons, or thesauri. It is a promising technique for classifying and retrieving the large volumes of clinical text.
Abstracting and Indexing↗
Obesity and benign prostatic hyperplasia.
Abdominal obesity increases the estrogen-to-androgen ratio and may increase sympathetic nervous activity, both hypothesized to influence the development of benign prostatic hyperplasia and the severity of urinary obstructive symptoms. In 1986 and 1987, men aged 40-75 years who were participants in the Health Professionals Follow-up Study and who were without prior diagnosis of cancer or prostatectomy provided data on weight, height, and waist and hip circumferences. The men were followed for incidence of prostatectomy for benign prostatic hyperplasia up to January 1992. In addition, the frequency and severity of symptoms of urinary obstruction were assessed among respondents to a questionnaire in 1992. Among 25,892 men who provided complete information for both surgery and symptoms, 837 men had surgery for benign prostatic hyperplasia, and 2,581 of those without surgery reported frequent urinary symptoms. After adjustment for age, smoking, and body mass index, abdominal obesity was related to prostatectomy (odds ratio (OR) = 2.38, 95% confidence interval (CI) 1.42-3.99, for those with a waist circumference > or = 43 inches (109 cm) relative to those with a waist circumference < 35 inches (89 cm); p trend < 0.0001) and with frequent urinary symptoms among those without prostatectomy (OR = 2.00, 95% CI 1.47-2.72; p < 0.0001). Body mass index, hip circumference, and waist-to-hip ratio were not associated with benign prostatic hyperplasia independently of waist circumference. These results suggest that abdominal obesity in men may increase the frequency and severity of urinary obstructive symptoms and may increase the likelihood that such obese men will undergo a prostatectomy.
Anthropometry↗
Prostate cancer in Rochester, Minnesota (USA), from 1935 to 1989: increases in incidence related to more complete ascertainment.
Prostate cancer incidence among White men in the United States climbed steadily from 45 per 10(5) person-years (PY) during 1945-54 to 102 per 10(5) PYs in 1988. To determine whether this increase might be the result of changing diagnostic practices, we examined trends in incidence and method of diagnosis in Rochester, Minnesota (US), from 1935 to 1989. We found a parallel increase in Rochester in non-autopsy diagnoses from 44 (95 percent confidence interval [CI] = 29-58) cases per 10(5) PYs in 1935-44 to 71 (CI = 52-89) cases per 10(5) PYs in 1985-87 which was driven by diagnoses prompted by digital rectal examination. There was no evidence that an increasing proportion of cases was found as the result of procedures to treat the symptoms of benign prostatic hyperplasia. Including autopsy diagnoses, incidence was stable over this extended interval and was 77 per 10(5) PYs (CI = 58-97) in 1935-44 and 72 per 10(5) PYs (CI = 53-91) in 1985-87. Incidence more than doubled after introduction of diagnostic serum prostate-specific antigen (PSA) assay and was 179 per 10(5) PYs (CI = 145-214) in 1988-89. We conclude that prostate-cancer incidence rates are influenced strongly by diagnostic practices and that national increases could reflect, to a large extent, more complete and earlier ascertainment rather than more frequent disease.
Adult↗
Medical data and knowledge management by integrated medical workstations: summary and recommendations.
The health care professional workstation will function as an interface between the user and the patient data as well as an interface pertinent medical knowledge. Appropriate knowledge focus will require the workstation to recognize the concepts and structure of patient data, and understand the scope and access methods of knowledge sources. Issues are organized around five major themes: (i) structure, (ii) reliability and validation, (iii) views, (iv) location, and (v) ethical and legal. Conventional database representations can effectively address data structure and format variations that will inevitably persist in local data stores. The reliability of data and the validation of knowledge are critical issues that may determine the ultimate utility of clinical workstations. Alternative views of patient information and knowledge sources represent the true power of an intelligent data portal, represented by a well-designed clinical workstation. Both data and knowledge are optimally represented in decentralized information networks, although the confidentiality and ownership of this information must be respected. Evolutionary progress toward consistent representations of knowledge and patient data will be facilitated by the establishment of self-documentation standards for the developers of data encoding systems and knowledge sources, perhaps extended from the preliminary model afforded by the Unified Medical Language System (UMLS).
Computer Security↗
Cigarette smoking and prostatism: a biphasic association?
OBJECTIVE: To evaluate the association between cigarette smoking and prostatism in a community-based setting using standardized urinary symptom scores, peak urinary flow rates, and prostatic volume as indicators of disease. METHODS: A population-based cohort of 2,115 Caucasian men aged forty to seventy-nine years from Olmsted County, Minnesota, was administered a previously validated questionnaire that elicited information on frequency of urinary symptoms (approximating the American Urological Association's symptom index), and a detailed history on cigarette smoking, including both amount and pack-years of smoking. Peak urinary flow rates were measured by a standard uroflowmeter (Dantec 1000). The prostatic volume was measured for a subsample of 471 men by transrectal ultrasound. RESULTS: Compared to never-smokers, smokers were less likely to have moderate to severe urinary symptoms (age-adjusted odds ratio 0.82; 95% confidence interval [CI] 0.61 to 1.08). This varied by smoking intensity, however; in men who smoked less than 1 pack a day the age-adjusted odds ratio was 0.53 (95% CI 0.33 to 0.83) and among men smoking 1 to 1.4 packs a day, the odds ratio was 0.87 (95% CI 0.56 to 1.36). For men who smoked 1.5 packs or more a day, the odds ratio was elevated at 1.32 (95% CI 0.84 to 2.07). Smokers were less likely to have peak flow rates less than 15 mL/sec compared with never-smokers (age- and voided volume-adjusted odds ratio 0.48; 95% CI 0.35 to 0.66), or prostatic volume greater than 40 mL (odds ratio 0.54; 95% CI 0.19 to 1.55). CONCLUSIONS: These data from a community-based sample suggest that light or moderate smokers are less likely to have moderate to severe prostatism, whereas heavy smokers are at least as likely to have moderate to severe prostatism compared with never-smokers.
Adult↗
Natural history of prostatism: worry and embarrassment from urinary symptoms and health care-seeking behavior.
OBJECTIVE: To assess the interrelationships among psychosocial symptoms of worry and embarrassment about urinary function, prevalent urinary symptoms, psychological well-being, and health care-seeking behavior in a population-based cohort of men. METHODS: A cohort of 2,119 men aged forty to seventy-nine years, randomly selected from the Olmsted County, Minnesota population between December 1989 and March 1991, were administered a previously validated questionnaire that elicited information about the frequency of urinary symptoms, the degree to which they were perceived as a bother, and if the participant had seen a doctor in the previous twelve months for evaluation of any of these urinary symptoms. Psychological well-being was assessed by a subset of the Psychological General Well-Being Index, and sociodemographic information was also sought. RESULTS: Urinary symptom indices (measured by American Urological Association frequency and bother scores and psychological general well-being subscales) were significantly associated with worry and embarrassment about urinary symptoms in bivariate analyses. Multiple logistic regression analyses demonstrated that men with moderate or severe urinary symptoms or impaired psychological well-being were more likely to be worried or embarrassed about their urinary symptoms than men with mild symptoms. Furthermore, men who were worried about their urinary function were more likely to have sought medical care for their symptoms than men who were not worried. The association between health care-seeking behavior and embarrassment was especially strong among men with little bother associated with their urinary symptoms. CONCLUSIONS: Worry and embarrassment about urinary symptoms reflect quality-of-life issues that appear important in the health care-seeking behavior of men with prostatism. The results underscore findings that prevalent urinary symptoms alone do not determine a man's health care-seeking behavior, and treatment for psychosocial symptoms may be beneficial in some men with symptoms of prostatism.
Adult↗
Effect of several recruitment strategies on response rates at baseline in a prospective cohort investigation. The Olmsted County Study of Urinary Symptoms and Health Status among Men.
Epidemiologic survey response rates were studied in relation to maneuvers introduced to improve acceptance: (a) variation in invitation letters, (b) the use of a brochure with the recruitment mailing, and (c) options for interview location. The baseline population-based survey of a prospective cohort investigation of the natural history of benign prostatic hyperplasia was used. Invitations to participate were mailed to eligible, randomly selected men aged 40 to 79 years from the Olmsted County, Minnesota, population during 1989 to 1991. Of the 3874 men identified, 2119 (55%) participated. Overall, there was no difference in response rate according to invitation characteristics (chi 2(5) = 8.02, P = 0.16). Nevertheless, response rates varied with age (chi 2(7) = 30.9, P < 0.001) and home location (rural versus Rochester city; chi 2(1) = 76.9, P < 0.001). This suggests the innovations used to bolster acceptance did not materially improve response rates. Further, since response rates were highest for men aged 60 to 74 years, men with more symptoms and free time may have joined the cohort more often than others.
Adult↗
The natural history of prostatism: the effects of non-response bias.
BACKGROUND: In epidemiological studies, non-response may raise the question of generalizability to the target population. Most investigations have not been able to access data that could provide information about the potential impact of non-response bias. METHODS: A 55% response rate was realized at baseline for a prospective cohort investigation of the natural history of benign prostatic hyperplasia in Olmsted County, Minnesota, during 1989-1991 (the Olmsted County Study of Urinary Symptoms and Health Status Among Men). This prompted a preliminary study of potential non-response bias among full participants, partial participants and complete non-responders. The medical diagnostic index maintained by the Rochester Epidemiology Project was used to ascertain the prevalence of specific conditions in the 9 years prior to study inception. RESULTS: The age-adjusted period prevalence rate for benign prostatic hyperplasia (%) was 9.6 (95% confidence interval [CI]: 8.1-11.0) for full participants, 8.2 (95% CI: 5.8-10.6) for partial participants and 5.3 (95% CI: 3.6-6.9) for complete non-responders. Other urologic diagnoses followed the same pattern. However, age-adjusted prevalence rates for general medical examination history and major non-urologic morbidities were decidedly similar across response groups. CONCLUSIONS: These data suggest response may have been driven, in part, by concerns about urologic disease. However, the similarity in non-urologic diagnoses and general medical examinations provide some preliminary reassurance that the 55% response rate did not necessarily compromise generalizability.
Adult↗
Lower-extremity motor neuropathy associated with surgery performed on patients in a lithotomy position.
BACKGROUND: Motor neuropathy of a lower extremity is well-recognized as a potential complication of procedures performed on patients in a lithotomy position. Most of this awareness is based on anecdotal reports, however, and the incidence and risk factors for this complication have not been reported. METHODS: We retrospectively reviewed the perioperative courses of 198,461 consecutive patients who underwent 1 of 56 surgical procedures historically performed on patients in a lithotomy position at the Mayo Clinic, Rochester, Minnesota, from 1957 to 1991 inclusive. The medical diagnoses of patients who had procedures in a lithotomy position were scanned for 26 diagnoses associated with neuropathy. Persistent neuropathy of the lower extremity was defined as a motor deficit of at least 3 months' duration. Risk factors anecdotally associated with persistent neuropathy were analyzed by comparing identified cases of neuropathy to controls in a 1:3 case-control study. RESULTS: Persistent neuropathies after procedures performed on patients in a lithotomy position were identified in 55 cases for a rate of 1 per 3,608. Multivariate risk factors for development of a persistent neuropathy of a lower extremity included duration in lithotomy of 4 h or longer, a body mass index (kilograms per squared meter) of 20 or less, and a history of smoking within 30 days of the procedure. Regional anesthetic techniques were not found to be associated with an increased risk of neuropathy. Of the 53 patients who lived at least 1 yr after their procedure, 24 (45%) required either prosthetic or ambulatory support for persistent foot drop or leg weakness. CONCLUSIONS: These data suggest that prolonged duration in lithotomy and patient risk factors, including very thin body habitus and smoking in the preoperative period, are associated with the development of a lower-extremity neuropathy after procedures performed on patients in a lithotomy position. A reduction of time in the lithotomy position may be particularly worthwhile for patients with these risk factors.
Adolescent↗
Correlation between urinary flow rate, voided volume, and patient age in a community-based population.
This investigation is unique in that is the first study to use a large number of randomly chosen men from the community to establish the relationship between: 1) urinary flow rate and voided volume, 2) urinary flow rate and patient age, 3) voided volume and patient age, and 4) the time to achieve peak urinary flow rate and patient age. The results clearly indicate that both the peak and mean urinary flow rate decreases with advancing age. The voided volume also diminishes with increasing age. The time required to achieve the peak urinary flow rate, however, appears to be independent of the patient's age. Irrespective of age, approximately 9 seconds are required to achieve the maximum urinary flow rate. Because the urinary flow rate is dependent upon both the quantity of urine voided and the patient's age, it is necessary to account for the influence of both parameters when establishing the "normal range" for peak urinary flow rate. To this end, nomograms estimating the peak urinary flow rate percentile as a function of voided volume and patient age have been generated and are included in this report. These nomograms, based on a large, randomly selected population, should make peak urinary flow rate a more reliable diagnostic modality for assessing bladder outlet obstruction. They also should be most useful to the practicing clinician when interpreting the results of a peak urinary flow rate determination for a patient presenting with symptoms of prostatism.
Adult↗
An application of Expert Network to clinical classification and MEDLINE indexing.
An effective and efficient learning method, Expert Network (ExpNet), is introduced in this paper. ExpNet predicts the related categories of an arbitrary text based on a search of its nearest neighbors in a set of training texts, and a reasoning from the expert-assigned categories of these neighbors. Evaluations in patient-record text classification and MEDLINE document indexing show a performance of ExpNet in recall and precision comparable to the Linear Least Squares Fit (LLSF) mapping method, and significantly better than other methods tested. We also observed that ExpNet is much more efficient than LLSF in computation. The total training and testing time on the patient-record text collection (6134 texts) was 4 minutes for ExpNet versus 96 minutes for LLSF; on the MEDLINE document collection (2344 documents), the total time was 15 minutes for ExpNet versus 4.6 hours for LLSF. It is evident in this study that human knowledge of text categorization can be statistically learned without expensive computation, and that ExpNet is such a solution.
Abstracting and Indexing↗
An evaluation of computer assisted clinical classification algorithms.
The Mayo Clinic has a long tradition of indexing patient records in high resolution and volume. Several algorithms have been developed which promise to help human coders in the classification process. We evaluate variations on code browsers and free text indexing systems with respect to their speed and error rates in our production environment. The more sophisticated indexing systems save measurable time in the coding process, but suffer from incompleteness which requires a back-up system or human verification. Expert Network does the best job of rank ordering clinical text, potentially enabling the creation of thresholds for the pass through of computer coded data without human review.
Abstracting and Indexing↗
A prospective study of dietary fat and risk of prostate cancer.
BACKGROUND: The strong correlation between national consumption of fat and national rate of mortality from prostate cancer has raised the hypothesis that dietary fat increases the risk of this malignancy. Case-control and cohort studies have not consistently supported this hypothesis. PURPOSE: We examined prospectively the relationship between prostate cancer and dietary fat, including specific fatty acids and dietary sources of fat. We examined the relationship of fat consumption to the incidence of advanced prostate cancer (stages C, D, or fatal cases) and to the total incidence of prostate cancer. METHODS: We used data from the Health Professionals Follow-up Study, which is a prospective cohort of 51529 U.S. men, aged 40 through 75, who completed a validated food-frequency questionnaire in 1986. We sent follow-up questionnaires to the entire cohort in 1988 and 1990 to document new cases of a variety of diseases and to update exposure information. As of January 31, 1990, 300 new cases of prostate cancer, including 126 advanced cases, were documented in 47855 participants initially free of diagnosed cancer. The Mantel-Haenszel summary estimator was used to adjust for age and other potentially confounding variables. Multiple logistic regression was used to estimate relative risks (RRs) when controlling simultaneously for more than two covariates. RESULTS: Total fat consumption was directly related to risk of advanced prostate cancer (age- and energy-adjusted RR = 1.79, with 95% confidence interval [CI] = 1.04-3.07, for high versus low quintile of intake; P [trend] = .06). This association was due primarily to animal fat (RR = 1.63; 95% CI = 0.95-2.78; P [trend] = .08), but not vegetable fat. Red meat represented the food group with the strongest positive association with advanced cancer (RR = 2.64; 95% CI = 1.21-5.77; P = .02). Fat from dairy products (with the exception of butter) or fish was unrelated to risk. Saturated fat, monounsaturated fat, and alpha-linolenic acid, but not linoleic acid, were associated with advanced prostate cancer risk; only the association with alpha-linolenic acid persisted when saturated fat, monounsaturated fat, linoleic acid, and alpha-linolenic acid were modeled simultaneously (multivariate RR = 3.43; 95% CI = 1.67-7.04; P [trend] = .002). CONCLUSION: The results support the hypothesis that animal fat, especially fat from red meat, is associated with an elevated risk of advanced prostate cancer. IMPLICATIONS: These findings support recommendations to lower intake of meat to reduce the risk of prostate cancer. The potential roles of carcinogens formed in cooking animal fat and of alpha-linolenic acid in the progression of prostate cancer need to be explored.
Adult↗
Serum prostate-specific antigen in a community-based population of healthy men. Establishment of age-specific reference ranges.
OBJECTIVE: To define the characteristics of serum prostate-specific antigen (PSA) in a population of healthy men without clinically evident prostate cancer, but who are at risk for developing the malignancy. The influence of patient age and prostatic size on the serum PSA concentration was assessed in order to use PSA more appropriately to detect clinically significant prostate cancer at an early, potentially curable stage. DESIGN: Prospective, community-based study. PARTICIPANTS: Between December 1989 and March 1991, 2119 healthy men aged 40 to 79 years from Olmsted County, Minnesota, were entered into a prospective study to assess the natural history of benign prostatic hyperplasia. Of these, 537 (25%) were randomly chosen to participate in a detailed clinical examination that included a serum PSA determination (Tandem-R PSA assay), digital rectal examination, and transrectal ultrasonography. Four hundred seventy-one (88%) completed the prostatic evaluation and had no evidence of prostate cancer by any of these three diagnostic tests; these men formed the study population on which all analyses were performed. MAIN OUTCOME MEASURE: Serum PSA concentration, prostatic volume, and PSA density (serum PSA level/prostatic volume) as a function of patient age. RESULTS: The serum PSA concentration is correlated with patient age (r = .43; P < .0001) and prostatic volume (r = .55; P < .0001). Prostatic volume, in turn, is directly correlated with patient age (r = .43; P < .0001), whereas the PSA density value is only weakly correlated with patient age (r = .25; P < .001). For a healthy 60-year-old man with no evidence of prostate cancer, the serum PSA concentration increases by approximately 3.2% per year (0.04 ng/mL per year). The recommended reference range for serum PSA (95th percentile) for men aged 40 to 49 years is 0.0 to 2.5 ng/mL; for 50 to 59 years, 0.0 to 3.5 ng/mL; 60 to 69 years, 0.0 to 4.5 ng/mL; and 70 to 79 years, 0.0 to 6.5 ng/mL. CONCLUSIONS: The serum PSA concentration is directly correlated with patient age and prostatic volume, the latter of which also is directly related to age. Thus, rather than rely on a single reference range for men of all age groups, it is more appropriate to have age-specific reference ranges. These age-specific reference ranges have the potential to make serum PSA a more discriminating tumor marker for detecting clinically significant cancers in older men (increasing specificity) and to find more potentially curable cancers in younger men (increasing sensitivity).
Adult↗
A population-based study of health care-seeking behavior for treatment of urinary symptoms. The Olmsted County Study of Urinary Symptoms and Health Status Among Men.
OBJECTIVE: To determine the extent to which severity of urinary symptoms predicts a man's decision to seek medical care for urinary symptoms. DESIGN: Cross-sectional, population-based survey; the baseline component of a prospective cohort study. SETTING: Olmsted County, Minnesota (1990 population, 105,720), including the city of Rochester (population, 69,995) and surrounding rural townships. SUBJECTS: A population-based sample of men aged 40 to 79 years randomly selected within age- and residence-specific strata. INTERVENTION: A previously validated questionnaire that elicited information about the frequency and bother of urinary symptoms, sociodemographic information, and information regarding use of physician services in the last year. MAIN OUTCOME MEASURE: An affirmative response to any of 12 questions asking the subject if he had seen a physician in the last year because of specific urinary symptoms. MAIN RESULT: Symptom severity, whether measured by American Urologic Association frequency or bother score or by interference with daily activities, was a significant predictor of health care-seeking behavior for urinary symptoms, but was neither as sensitive nor as specific as would be ideal. After adjusting for symptom severity and sociodemographic characteristics, men aged 70 to 79 years were 4.6 times as likely (95% confidence interval, 2.1 to 10.1) as men aged 40 to 49 years to have sought health care because of urinary symptoms in the last year. CONCLUSION: While symptom severity is an important determinant of health care-seeking behavior for men with urinary symptoms, some additional factor or factors associated with age remain that may drive men to seek care for urinary symptoms. These factors may prove important in understanding the small-area variations in treatment of benign prostatic hyperplasia that have been noted by others.
Adult↗
Natural history of prostatism: factors associated with discordance between frequency and bother of urinary symptoms.
The objective of this study was to assess the association between frequency and bother of urinary symptoms in a population-based cohort of men and to identify psychosocial factors that are related to reporting heightened or subdued bother relative to symptom frequency. The survey was conducted among men aged forty to seventy-nine years in Olmsted County, Minnesota, the baseline component of a prospective cohort study. Men were queried about the frequency of urinary symptom occurrence and the perceived bother associated with the symptoms. A regression analysis of American Urologic Association (AUA) bother scores on AUA frequency scores demonstrated a tight correspondence (r2 = 0.71). Men with bother scores greater than predicted from their frequency scores were more likely to have sought health care for their urinary symptoms than men whose bother was close to predicted (14 versus 5 percent, respectively). These men with heightened bother were older, poorer, more anxious, and had lower general psychologic well-being scores than the men whose bother was similar to that expected from their reported frequency. Men whose bother was lower than would be expected were less likely to have sought health care for urinary symptoms in the past year (3%) but were of similar age and socioeconomic status as compared with men whose bother was close to expected. These men, however, were more depressed than men whose bother was commensurate with reported frequency. While the men who reported greater bother than expected from their symptom frequency were more likely to have sought medical care for urinary symptoms in the past year, it is not clear whether this greater health-care-seeking behavior is because bother captures an additional component of urologic disease or is a manifestation of psychosocial differences.
Adult↗
The prevalence of prostatism: a population-based survey of urinary symptoms.
To establish the age-specific prevalence of urinary symptoms among a community-based cohort of men, a randomly selected sample of men were screened and invited to participate in a longitudinal survey of urinary symptoms. The population of Olmsted County, Minnesota, as enumerated by the Rochester Epidemiology Project, formed the sampling base for this study. Men between 40 and 79 years old with no history of prostate or other urological surgery, and who also were free of conditions associated with neurogenic bladder were invited to participate. A previously validated questionnaire was completed by the subject. Urine flow measures, current medications and family histories of urinary disease were also obtained. Nonresponse corrected scores for a composite of obstructive symptoms showed moderate to severe symptomatology among 13% of the men 40 to 49 years old and 28% of those older than 70 years. Prostatism is a highly prevalent symptom complex among unselected men in the community. The specific urinary symptoms of nocturia, weak stream, restarting, urgency and sensation of incomplete emptying are strongly age-related and, therefore, may be predictive of a prostatic disease process.
Adult↗