Advanced Machine Learning Tools to Monitor Biomarkers of Dysphagia: A Wearable Sensor Proof-of-Concept Study

Introduction

Difficulty swallowing (dysphagia) occurs frequently in patients with neurological disorders and can lead to aspiration, choking, and malnutrition. Dysphagia is typically diagnosed using costly, invasive imaging procedures or subjective, qualitative bedside examinations. Wearable sensors are a promising alternative to noninvasively and objectively measure physiological signals relevant to swallowing. An ongoing challenge with this approach is consolidating these complex signals into sensitive, clinically meaningful metrics of swallowing performance. To address this gap, we propose 2 novel, digital monitoring tools to evaluate swallows using wearable sensor data and machine learning.

Methods

Biometric swallowing and respiration signals from wearable, mechano-acoustic sensors were compared between patients with poststroke dysphagia and nondysphagic controls while swallowing foods and liquids of different consistencies, in accordance with the Mann Assessment of Swallowing Ability (MASA). Two machine learning approaches were developed to (1) classify the severity of impairment for each swallow, with model confidence ratings for transparent clinical decision support, and (2) compute a similarity measure of each swallow to nondysphagic performance. Task-specific models were trained using swallow kinematics and respiratory features from 505 swallows (321 from patients and 184 from controls).

Results

These models provide sensitive metrics to gauge impairment on a per-swallow basis. Both approaches demonstrate intrasubject swallow variability and patient-specific changes which were not captured by the MASA alone. Sensor measures encoding respiratory-swallow coordination were important features relating to dysphagia presence and severity. Puree swallows exhibited greater differences from controls than saliva swallows or liquid sips (p < 0.037).

Discussion

Developing interpretable tools is critical to optimize the clinical utility of novel, sensor-based measurement techniques. The proof-of-concept models proposed here provide concrete, communicable evidence to track dysphagia recovery over time. With refined training schemes and real-world validation, these tools can be deployed to automatically measure and monitor swallowing in the clinic and community for patients across the impairment spectrum.

Social determinants of older adults' awareness of community support services in Hamilton, Ontario

Community support services (CSSs) have been developed in Canada and other Western nations to enable persons coping with health or social issues to continue to live in the community. This study addresses the extent to which awareness of CSSs is structured by the social determinants of health. In a telephone interview conducted in February-March 2006, 1152 community-dwelling older adults (response rate 12.4%) from Hamilton, Ontario, Canada were made to read a series of four vignettes and were asked whether they were able to identify a CSS they may turn to in that situation. Across the four vignettes, 40% of participants did name a CSS as a possible source of assistance. Logistic regression was used to determine factors related to awareness of CSSs. Respondents most likely to have awareness of CSS include the middle-aged and higher-income groups. Being knowledgeable about where to look for information about CSSs, having social support and being a member of a club or voluntary organisations are also significant predictors of awareness of CSSs. Study results suggest that efforts be made to improve the level of awareness and access to CSSs among older adults by targeting their social networks as well as their health and social care providers.

Where would you turn for help? Older adults' awareness of community support services

Previous findings on older adults' awareness of community support services (CSSs) have been inconsistent and marred by acquiescence or over-claiming bias. To address this issue, this study used a series of 12 vignettes to describe common situations faced by older adults for which CSSs might be appropriate. In telephone interviews, 1,152 adults aged 50 years and over were read a series of vignettes and asked if they were able to identify a community organization or agency that they may turn to in that situation. They were also asked about their most important sources of information about CSSs. The findings show that, using a vignette methodology, awareness of CSSs is much lower than previously thought. The most important sources of information about CSSs included information and referral sources, the telephone book, doctors' offices, and word of mouth.

Do socioeconomic characteristics modify the short term association between air pollution and mortality? Evidence from a zonal time series in Hamilton, Canada

STUDY OBJECTIVE

To assess the short term association between air pollution and mortality in different zones of an industrial city. An intra-urban study design is used to test the hypothesis that socioeconomic characteristics modify the acute health effects of ambient air pollution exposure.

DESIGN

The City of Hamilton, Canada, was divided into five zones based on proximity to fixed site air pollution monitors. Within each zone, daily counts of non-trauma mortality and air pollution estimates were combined. Generalised linear models (GLMs) were used to test mortality associations with sulphur dioxide (SO(2)) and with particulate air pollution measured by the coefficient of haze (CoH).

MAIN RESULTS

Increased mortality was associated with air pollution exposure in a citywide model and in intra-urban zones with lower socioeconomic characteristics. Low educational attainment and high manufacturing employment in the zones significantly and positively modified the acute mortality effects of air pollution exposure.

DISCUSSION

Three possible explanations are proposed for the observed effect modification by education and manufacturing: (1) those in manufacturing receive higher workplace exposures that combine with ambient exposures to produce larger health effects; (2) persons with lower education are less mobile and experience less exposure measurement error, which reduces bias toward the null; or (3) manufacturing and education proxy for many social variables representing material deprivation, and poor material conditions increase susceptibility to health risks from air pollution.

Capitation and primary care in Canada: financial incentives and the evolution of health service organizations

Alternative approaches to the funding, organization, and delivery of primary care have been the subject of ongoing discussion and debate in many industrialized nations for many years. One common recommendation has been to use capitation, as opposed to fee-for-service, as the payment method for physicians. In this study the authors use data from interviews with physicians and Ministry of Health officials to trace the evolution of Ontario's Health Service Organization (HSO) program, the only program of capitation-funded physician care in Canada. The program has developed in three phases: formation in the early 1970s, expansion in the late 1970s and throughout the 1980s, and restructuring in the 1990s. The analysis focuses on the perceptions and actions of policymakers and physicians who became involved with the program at different points in its evolution, and identifies how they perceived and responded to the financial incentives that were introduced to promote the program. This case study allows an examination of the shifting objectives, communications, perceptions, and responses of policymakers and stakeholders in changing contexts over a period of more than 20 years. The long history of the HSO program provides the opportunity to examine the factors that can cause financial incentives to go awry. The authors suggest how this case study offers lessons for financial incentive policymaking.

Perceived support needs of family caregivers and implications for a telephone support service

The purposes of this study were: to identify the perceived support needs of family caregivers of persons living with chronic illness (physical or cognitive) and receiving home-care services, and to describe the types of telephone services that would meet the expressed needs of caregivers. The qualitative design used semi-structured interviews. A total of 34 caregivers (mean age 62 years) participated in the study. The care recipients (mean age 78 years) were primarily the husband/wife or parent of the caregiver. The most commonly expressed caregiver needs were: a social life, instrumental support (e.g., respite, assistance with physical care, financial compensation), informational support, and emotional support. Most caregivers said they would use a telephone support service provided by a professional (71%) or a fellow caregiver (59%) if available. The results of this study support a pilot study and evaluation of a telephone support service for family caregivers.

Primary care in Canada: so much innovation, so little change

The development of Canadian primary care has been shaped by a series of policy legacies that continue to affect the possibilities for change in primary care through their cumulative effects on the health care system and the process of health policy development. The pursuit of radical systemwide change in the face of unfavorable circumstances (created in large part by those legacies) has resulted in missed opportunities for cumulative incremental change. While major changes in primary care policy seem unlikely in the near future, significant incremental change is possible, but it will require a reorientation of the policy development process.

Needs-based primary medical care capitation: development and evaluation of alternative approaches

OBJECTIVE

To develop and evaluate alternative methods of adjusting primary medical care capitation payments for variations in relative need for health care among enrolled practice populations.

METHODS

We developed alternative needs-based capitation formulae and applied them to a sample of capitation-funded primary care practices to assess each formula's performance against a reference standard of capitation payments based on age, sex and self-assessed health status of the enrolled populations. The alternative formulae were based on: (1) age and sex; (2) age, sex and individually-measured socioeconomic characteristics; (3) age, sex and socioeconomic characteristics imputed from census data for enrollees' neighbourhood of residence; (4) age, sex and standardized mortality ratio for enrollees' neighbourhood of residence.

RESULTS

Age/sex-adjusted capitation payments for the six practices studied ranged from 10% higher to 18% lower than the reference standard payments. Capitation formulae based on socioeconomic and mortality data did not perform consistently better than the current age/sex-based formula.

CONCLUSIONS

Primary medical care capitation payments adjusted only for age and sex do not reflect the relative health care needs of enrolled practice populations. Our alternative formulae based on socioeconomic and mortality data also failed to reflect relative needs. Methods that use other approaches to adjusting for differences in relative need among enrolled populations should be investigated.

Evaluating the effectiveness of 2 educational interventions in family practice

BACKGROUND

Structured feedback of information can produce change in physician behaviour. The objective of this study was to assess the effectiveness of 2 educational interventions for improving the quality of care provided by family physicians in Ontario: the Practice Assessment Report (PAR) and the Continuing Medical Education Plan (CMEP) with a follow-up visit by a mentor.

METHODS

The study was a randomized controlled trial. Physicians in the control group received only the PAR, whereas those in the experimental group received the PAR, CMEP and mentor interventions. The participants were 56 family physicians and general practitioners (27 in the PAR group and 29 in the CMEP group) in southern Ontario who agreed to participate in the interventions and provide data. A total of 2395 patients randomly sampled from the practices returned questionnaires and consented to have their medical records abstracted. The outcome measures were global scores in 4 areas--quality of care, charting, prevention and overall use of medications--and patient ratings of satisfaction with care and preventive practices. The measures were applied at the beginning (phase 1) and end (phase 2) of the study.

RESULTS

The mean global scores at the end of the study for the PAR group were 70.1% for quality of care, 84.7% for prevention, 77.7% for charting and 82.2% for overall use of medications. The corresponding scores for the CMEP group were 68.3%, 82.1%, 76.4% and 83.2%. In the patient satisfaction component, the personal care scores at phase 2 were 93.6% for the PAR group and 94.6% for the CMEP group. Examples of the scores for prevention for the PAR group were 98.3% for children's current immunization, 96.6% for blood pressure measured within the previous 5 years, 79.4% for referral of women of the appropriate age for mammography within the previous 2 years, and 58.4% for discussion about alcohol use. The corresponding scores for the CMEP group were 95.8%, 97.6%, 77.6% and 64.6%. The changes in mean scores between phase 1 and phase 2 ranged from -1.9 to 2.3 points. There were no significant differences between the 2 groups in phase 1 or phase 2 scores or in change in scores. A total of 64.3% of the physicians rated the PAR as useful, 26.5% found the CMEP to be useful, and 41.0% considered the mentor strategy to be a useful form of continuing medical education. Although changes in practice related to the PAR, CMEP or mentor were reported by some physicians, they were not related to chart audit or patient scores.

INTERPRETATION

Educational interventions based on quality-of-care assessments and directed to global improvements in quality of care did not result in improvements in the outcome measures. Educational interventions may have to be targeted to specific areas of the practice, with physicians being monitored and receiving ongoing feedback on their performance.

Selective opportunistic screening for hypercholesterolemia in primary care practice

OBJECTIVES

To assess the performance of selective opportunistic screening in a primary care group practice.

DESIGN

Cross-sectional survey of coronary heart disease risk factors and retrospective chart audit of cholesterol testing.

SETTING

Capitation-funded primary care group practice in Ontario, Canada.

SUBJECTS

7785 enrolled patients between the ages of 20 and 69 years.

INTERVENTION

Protocol-based selective opportunistic screening program for hypercholesterolemia of 45 months duration.

MAIN OUTCOME MEASURES

Targeting (proportion of screening tests that were appropriate), coverage (proportion of those meeting screening criteria who had a screening test performed), over-screening (proportion of those not meeting screening criteria who had a screening test performed), and screening ratio (likelihood that a screening test was performed on an individual who met screening criteria rather than one who failed to meet screening criteria).

RESULTS

64.7% of patients tested met the practice criteria for screening. 37.7% of patients who met the practice screening criteria were tested and 24.9% of those not meeting practice screening criteria had a cholesterol test performed. The screening ratio was 1.52.

CONCLUSION

Our findings bring into question the effectiveness of opportunistic approaches to preventive care.

Fielding standardized patients in primary care settings: lessons from a study using unannounced standardized patients to assess preventive care practices

OBJECTIVES

To document detection and suspicion rates of unannounced standardized patients visiting community-based practices.

DESIGN

Primary care physicians were recruited to participate in a study using standardized patients. Four standardized patient scenarios were used.

SETTING

Community-based primary care physicians' practices in southern Ontario between September 1994 and August 1995.

STUDY PARTICIPANTS

Sixty-two primary care physicians.

MAIN OUTCOME MEASURES

A 'believability' questionnaire completed after all four standardized patients had visited the practices.

RESULTS

Of the primary care physicians approached, 50% (62) agreed to participate. Twenty-one per cent of all visits were suspected as standardized patient encounters. Forty-six per cent suspected one or more standardized patients. Only five physicians (8%) suspected all four standardized patients. Reasons for suspecting standardized patients were associated with the characteristics of the physician's practices, the physician's practice profile and the standardized patient cover story.

CONCLUSION

The portrayal of asymptomatic patients seeking a new primary care physician presents unique challenges. Carefully constructed cover stories, and detailed knowledge of the local area and of the practices of the participating physicians is required to allow standardized patients cases to be tailored to fit into primary care settings without arousing suspicion.

Screening for hypercholesterolaemia in primary care: randomised controlled trial of postal questionnaire appraising risk of coronary heart disease

OBJECTIVES

To validate a self administered postal questionnaire appraising risk of coronary heart disease. To determine whether use of this questionnaire increased the percentage of people at high risk of coronary heart disease and decreased the percentage of people at low risk who had their cholesterol concentration measured.

DESIGN

Validation was by review of medical records and clinical assessment. The questionnaire appraising risk of coronary heart disease encouraged those meeting criteria for cholesterol measurement to have a cholesterol test and was tested in a randomised controlled trial. The intervention group was sent the risk appraisal questionnaire with a health questionnaire that determined risk of coronary heart disease without identifying the risk factors as related to coronary heart disease; the control group was sent the health questionnaire alone.

SETTING

One capitation funded primary care practice in Canada with an enrolled patient population of about 12 000.

SUBJECTS

Random sample of 100 participants in the intervention and control groups were included in the validation exercise. 5686 contactable patients aged 20 to 69 years who on the basis of practice records had not had a cholesterol test performed during the preceding 5 years were included in the randomised controlled trial. 2837 were in the intervention group and 2849 were in the control group.

MAIN OUTCOME MEASURES

Sensitivity and specificity of assessment of risk of coronary heart disease with risk appraisal questionnaire. Rate of cholesterol testing during three months of follow up.

RESULTS

Sensitivity of questionnaire appraising coronary risk was 87.5% (95% confidence interval 73.2% to 95.8%) and specificity 91.7% (81.6% to 97.2%). Of the patients without pre-existing coronary heart disease who met predefined screening criteria based on risk, 45 out of 421 in the intervention group (10.7%) and 9 out of 504 in the control group (1.8%) had a cholesterol test performed during follow up (P<0.0001). Of the patients without a history of coronary heart disease who did not meet criteria for cholesterol testing, 30 out of 1128 in the intervention group (2.7%) and 18 out of 1099 in the control group (1.6%) had a cholesterol test (P=0.175). Of the patients with pre-existing coronary heart disease, 1 out of 15 in the intervention group (6.7%) and 1 out of 23 in the control group (4.3%) were tested during follow up (P=0.851, one tailed Fisher's exact test).

CONCLUSIONS

Although the questionnaire appraising coronary risk increased the percentage of people at high risk who obtained cholesterol testing, the effect was small. Most patients at risk who received the questionnaire did not respond by having a test.

What factors influence primary care physicians' charges for their services? An exploratory study using standardized patients

OBJECTIVE

To determine the extent of variation in physicians' charges for health care encounters with unannounced standardized patients and factors associated with the variation.

DESIGN

Cross-sectional study.

SETTING

Family practices open to new patients within 1 hour's drive of Hamilton, Ont.

PARTICIPANTS

A stratified random sample of 125 physicians who had responded to an earlier survey regarding preventive care were invited to participate. Of the 125, 44 (35.2%) declined to participate, and an additional 19 (15.2%) initially consented but later withdrew because they closed their practices to new patients. Sixty-two physicians thus participated in the study.

INTERVENTION

Unannounced standardized patients posing as new patients to the practice visited study physicians' practices between September 1994 and August 1995, portraying 4 scenarios: 28-year-old woman, 52-year-old woman, 48-year-old man and 70-year-old man.

OUTCOME MEASURES

Physician characteristics, encounter characteristics and charges made for services.

RESULTS

The 62 physicians had 246 encounters with the standardized patients. Charges were made to the health insurance plan for services by 59 physicians for up to 4 encounters (215 encounters in all). Charges varied considerably both within and across patient scenarios. Time spent with the patient was an important factor predicting charges made (p < 0.01), although the effect of time spent on charges varied across scenarios (p < 0.01). Fee-for-service physicians charged more for their services than physicians who usually had alternative billing arrangements (p < 0.01). Female physicians charged more for their services than their male colleagues (p = 0.03). No relation was found between quality of preventive care and charges made (p = 0.15).

CONCLUSIONS

Physician-related factors are better able to account for the variability in charges for their services than patient-related factors. Physicians seeing comparable patients may earn much more or less than their colleagues because of differences in the services they provide and the way they apply the fee schedule. Quality-assurance techniques are likely needed to reduce the variability in charges seen and increase value for money spent in health care.

Provision of preventive care to unannounced standardized patients

OBJECTIVE

To examine the relation between physician, training and practice characteristics and the provision of preventive care as described in the guidelines of the Canadian Task Force on the Periodic Health Examination.

DESIGN

Cross-sectional study.

SETTING

Family practices open to new patients within 1 hour's drive of Hamilton, Ont.

PARTICIPANTS

A total of 125 family physicians were randomly selected from respondents to an earlier preventive care survey. Of the 125, 44 (35.2%) declined to participate, and an additional 19 (15.2%) initially consented but later withdrew when they closed their practices to new patients. Sixty-two physicians thus participated in the study.

INTERVENTION

Unannounced standardized patients posing as new patients to the practice visited study physicians' practices between September 1994 and August 1995, portraying 4 scenarios: 48-year-old man, 70-year-old man, 28-year-old woman and 52-year-old woman.

OUTCOME MEASURES

Proportion of preventive care manoeuvres carrying grade A, B, C, D and E recommendations from the Canadian Task Force on the Periodic Health Examination that were performed, offered or advised. A standard score was computed based on the performance of grade A and B manoeuvres (good or fair evidence for inclusion in the periodic health examination) and the non-performance of grade D and E manoeuvres (fair or good evidence for exclusion from the periodic health examination).

RESULTS

Study physicians performed or offered 65.6% of applicable grade A manoeuvres, 31.0% of grade B manoeuvres, 22.4% of grade C manoeuvres, 21.8% of grade D manoeuvres and 4.9% of grade E manoeuvres. The provision of evidence-based preventive care was associated with solo (v. group) practice and capitation or salary (v. fee-for-service) payment method. Preventive care performance was unrelated to physician's sex, certification in family medicine or problem-based (v. traditional) medical school curriculum.

CONCLUSIONS

Preventive care guidelines of the Canadian Task Force on the Periodic Health Examination have been incompletely integrated into clinical practice. Research is needed to identify and reduce barriers to the provision of preventive care and to develop and apply effective processes for the creation, dissemination and implementation of clinical practice guidelines.

Casting the screening net: separating big fish from little fish

Screening tests are a rapidly growing part of medical practice. If we are going to make the best use of resources, screening tests need to be considered in terms of effectiveness, efficiency and equity. We present a framework as a way to think about screening programmes. The framework expands on existing literature that recognizes two categories of screening: universal and opportunistic. By adding the dimension of 'selectivity', we identify four categories of screening: active non-selective (universal or mass screening), active selective, opportunistic non-selective and opportunistic selective. We illustrate the framework by categorizing screening recommendations for high serum cholesterol levels. We conclude there is no one ideal strategy for screening that simultaneously satisfies criteria of effectiveness, efficiency and equity. However, our framework allows a systematic consideration and balancing of these objectives in the development and assessment of screening programs. In this way, it may assist decision-makers by making this trade-off more explicit.

Is cervicography a useful diagnostic test? A systematic overview of the literature

BACKGROUND

The appropriate approach to women with mild dyskaryotic changes on Papanicolaou smear is subject to controversy. Our aim was to assess the usefulness of cervicography as a diagnostic test in detecting cervical cancer or its precursors.

METHODS

We undertook an extensive literature search looking for pertinent studies of cervicography published between 1966 and 1996. Eligible studies included those in which the reference standard (colposcopy) was done on all patients. The following information was calculated: sensitivity, specificity, positive predictive value, negative predictive value, disease prevalence, and likelihood ratios.

RESULTS

Cervicography has a high false-positive rate. This rate ranged from 8.2 to 61.0 percent (median 42.1 percent) for any dysplasia and 9.8 to 63.4 percent (median 50.6 percent) for high-grade cervical lesions. Likelihood ratios for a positive test result ranged from 1.0 to 10.6. Likelihood ratios for a negative result ranged from 0.02 to 1.0.

CONCLUSIONS

The usefulness of cervicography is heavily dependent on the approach used to evaluate abnormal findings on a Papanicolaou smear. If a provider typically offers colposcopy to all patients with low-grade cytologic findings on a Papanicolaou smear, cervicography will decrease colposcopy use and allow for detection of cases of high-grade dysplasia missed by the index Papanicolaou smear. If a provider typically uses watchful waiting with repeat Papanicolaou smears for all patients who have low-grade cytologic findings, cervicography will substantially increase the use of colposcopy. Many of these colposcopies will be done as a result of false-positive cervigrams.

The effects of whirlpools baths in labor: a randomized, controlled trial

BACKGROUND

Showers and tubs in labor were not generally used in our center. When three whirlpool baths (Jacuzzis) were ordered as part of our renovations, a randomized, controlled trial was initiated to explore their effects on narcotic and epidural requirements.

METHODS

This study employed an intent-to-treat design, and the sample size was estimated to account for the fact that some women would be unable to use the tub. The experimental group of 393 women was offered the tub during labor and the control group of 392 women received conventional care.

RESULTS

No births occurred in the tub. The tub group required fewer pharmacologic agents than controls (66% vs 59%, p = 0.06), experienced fewer deliveries by forceps and vacuum (p = 0.019), and were more likely to have an intact perineum than the standard-care group (p = 0.019). Labor was longer for the tub group (p = 0.003), who coincidentally were more primiparous and in earlier labor on admission. No differences were noted in the low rates of maternal and newborn signs of infection in women with ruptured membranes. A subset of mothers expressed satisfaction with the tub experience and labor support. The cesarean rate among both groups was lower (8.9%) than our overall rate (16.6%) during the study period.

CONCLUSIONS

Whirlpool baths in labor have positive effects on analgesia requirements, instrumentation rates, condition of the perineum, and personal satisfaction. Further study is being planned.

HIV testing practices of primary care physicians: an Ontario survey

To determine whether physicians are knowledgeable about the risk factors associated with HIV and whether perceived testing practices coincide with testing guidelines, 1,236 physicians were surveyed about which patients they would recommend for HIV testing. A total of 480 usable responses were obtained (response rate of 50% of the eligible sample). Most would suggest testing to partners of intravenous drug users, patients who received blood transfusions between 1978 and 1985, homosexuals and bisexuals, and patients with more than two sexually transmitted diseases. Only 46.4% would suggest testing to patients with more than two sexual partners, and 65.8% would test anyone who asks. Other patients to whom physicians would recommend testing were listed by 16.2%. Logistic regression (F-step) was used to examine the relationship between physician characteristics and likelihood of recommending testing. As a rule, physicians are knowledgeable about the major risk factors and would recommend testing according to guidelines. However, there may be a difference between questionnaire responses and actual practice.

Do physician-payment mechanisms affect hospital utilization? A study of Health Service Organizations in Ontario

OBJECTIVES

To determine whether payment of primary care physicians based on capitation, with an additional incentive payment for low hospital-utilization rates, resulted in lower hospital-utilization rates among patients of these physicians than among patients of physicians still paid on a fee-for-service basis.

DESIGN

Retrospective cohort study.

SETTING

Capitation-based and fee-for-service primary care practices in Ontario.

SUBJECTS

Thirty-nine physicians whose method of payment was converted from fee-for-service to capitation during the period from June 1985 to January 1989 and 7 physicians who remained in fee-for-service practice, two of whom were matched with one physician in capitation-based practice on the basis of practice location, type of practice (academic v. community), hours of practice (part-time v. full-time), years since graduation, physician group size, practice size (number of patients), type of group (primary care v. multispecialty), sex, certification in family medicine, country of graduation (Canada v. other) and age. One physician in capitation-based practice was matched with only one physician in fee-for-service practice.

OUTCOME MEASURES

Annual hospital-utilization rates (hospital separations or hospital days per 1000 patients in each practice) for the physicians paid on a capitation basis 3 years before, 1 year before and 3 years after they converted from fee-for-service payment and at corresponding periods for the matched physicians still paid on a fee-for-service basis.

RESULTS

The mean annual rate of hospital days used, adjusted for the age and sex of patients as well as for their social-program-recipient status, fell from 1085 per 1000 patients (3 years before the conversion date) to 1030 (1 year before conversion) and to 954 (3 years after conversion) in capitation-based practices. For the matched physicians in fee-for-service practice, the rates during the corresponding periods were 1085, 1035 and 956 hospital days per 1000 patients. The pattern was similar for rates of hospital separations, adjusted for patient's age, sex and social-program-recipient status. There were no statistically significant differences between the rates of hospital utilization among patients of physicians in capitation-based practices and the rates among those of physicians in fee-for-service practices during each of the three periods, nor were there significant differences in the changes in rates.

CONCLUSION

Capitation payment, with an additional incentive payment to encourage low hospital-utilization rates, did not reduce hospital use. Factors other than the method of physician payment appear to be responsible for the variations in hospital utilization among practices.

Drosophila melanogaster genes encoding three troponin-C isoforms and a calmodulin-related protein

Using low-stringency hybridization and polymerase chain reaction (PCR)-based DNA amplification, we have isolated three Drosophila melanogaster genes that encode troponin-C isoforms and one specifying a protein that is closely related to calmodulin. Two of the troponin-C genes, located within the 47D and 73F subdivisions of chromosomes 2 and 3, respectively, encode very closely related isoforms. That specified by the 47D gene accumulates almost exclusively in larval muscles, while that encoded by the 73F gene is present in both larvae and adults. The third gene, located within the 41C subdivision of chromosome 2, encodes a more distantly related troponin-C isoform that accumulates only within adults. The gene that encodes the calmodulin-related protein is located within the 97A subdivision of chromosome three. The protein encoded by this gene has a different primary sequence from that of conventional calmodulin, which is specified by a gene located within the 49A subdivision of chromosome 2. Our report is the first to describe insect troponin-C isoforms and further avails genetic methods for investigating the in vivo functions of the troponin-C/myosin light-chain/calmodulin protein superfamily.

Predictors of driving while intoxicated (DWI) among American Indians in the northwest

This study compares DWI arrest records for American Indians to those of the general population in Washington State. Within the period January 1987 through December 1987, 1,067 American Indians were arrested for DWI. This sample was compared for age, gender, and occupational status to 28,130 total DWI arrestees during the same period. The data indicate that American Indians were the most over-represented population as they were two-and-one-half times as likely to be arrested for DWI, compared to overall DWI arrest population. The population of American Indians arrested for DWI was three times as likely to be unemployed as compared to the resident labor force of all American Indians. This research supports the conclusion that DWI arrests may be viewed as a symptom of alcohol misuse, abuse, or chemical dependency for American Indians, and that a DWI prevention approach should include education, prevention, intervention, treatment, aftercare, and law enforcement efforts that are sensitive to tribal diversity.

Determinants of intact parathyroid hormone and free 1,25-dihydroxyvitamin D levels in mild and moderate renal failure

Parameters of calcium and phosphate metabolism were measured in 27 patients with mild renal failure [glomerular filtration rate (GFR) 40-90 ml/min], 12 patients with moderate renal failure (GFR 20-39 ml/min) and in 12 healthy subjects. GFR was determined by technetium-99m diethylenetriamine penta-acetic acid clearance. Intact parathyroid hormone (PTH) was measured by a sensitive immunochemiluminometric assay and somatomedin-C was determined by radioimmunoassay. Both 1,25-dihydroxyvitamin D [1,25(OH)2D] and vitamin-D-binding protein were measured allowing calculation of the free 1,25(OH)2D index. By linear regression and multivariate analysis, PTH was negatively and independently correlated with GFR, plasma bicarbonate and 25-hydroxyvitamin D [25(OH)D] while free 1,25(OH)2D was positively correlated with GFR. Increased PTH secretion and reductions in 1,25(OH)2D were present in mild renal failure patients before any changes in plasma calcium, phosphate and bicarbonate were noted. Plasma alkaline phosphatase was significantly higher in mild chronic renal failure patients compared to normal subjects, possibly indicating early effects of the secondary hyperparathyroidism on the skeleton. Somatomedin-C did not correlate with the free 1,25(OH)2D index or a measure of 1,25(OH)2D production. It is concluded that the secondary hyperparathyroidism which occurs very early in the onset of chronic renal failure may be due to a reduction in the circulating concentration of 1,25(OH)2D consequent upon the renal failure. Low plasma bicarbonate and 25(OH)D also appear to be determinants of a raised PTH concentration. The compensatory increase in PTH presumably maintains extracellular calcium and phosphate levels constant but with possible deleterious effects on the skeleton.

HLA-DR and -DQ genotyping in anti-GBM disease

Anti-GBM disease has been associated with the HLA genes of the major histocompatibility complex (MHC) in previous serological studies, with an increased incidence of HLA-DR2 in patients. In this study, 36 patients with anti-GBM disease were genotyped by restriction fragment length polymorphism (RFLP) analysis using cDNA probes for DRB, DQA, and DQB. The frequency of HLA-DRw15(Dw2), a split of DR2, was significantly increased in the patients compared with the controls (63.9 per cent versus 23.3 per cent, chi 2 = 22.4, p(corr) less than 0.0001), and all but one of the patients were positive for either DRw15(Dw2) or DR4 (p less than 0.0001). The frequencies of the remaining DR antigens were not decreased randomly, with a significant decrease in DR7 in the patient group (chi 2 = 8.6, p(corr) less than 0.05). The closely linked gene HLA-DQw6 was found to be significantly increased in frequency in the patients compared with the controls (p(corr) less than 0.0001). No correlations could be made between the genetic data and clinical features of the disease.

A needs-based methodology for allocating health care resources in Ontario, Canada: development and an application

In an attempt to limit its health care expenditures, Ontario is, as one option, exploring the possibilities of a capitated system for service delivery payments as opposed to the present mixture of global budgets and fee-for-service. After reviewing the literatures on capitation (primarily American) and on resource allocation (primarily British), the paper sets out to establish a capitation rate, based on 'need' and not prior use, for a range of health services in the northern Ontarian community of Fort Frances-Rainy River. The difficulties and limitations of the needs-based approach are explored. The results reported show the setting of the local population characteristics against provincial average health care utilization data to generate expected use rates, which are then adjusted for need and other factors, particularly relative costs and sparsity. Finally these adjusted rates are applied to current provincial expenditures to derive a target share. This target is then expressed in relation to the planning population to derive the capitation rate.

A pilot home-based geriatric health screening project in primary care

Regular multidimensional screening of the elderly for undetected health problems has the potential for delaying functional deterioration and improving the quality of life, but has not been evaluated rigorously. This pilot study examined the amount and type of unmet health care need discovered by home-based screening of 100 family practice patients aged 75 and over. Although 96 per cent of patients had some health problems, only 71 per cent had problems that needed further intervention. Of these, the majority were problems in the area of psychosocial function, independence, and lifestyle. Age, sex, and frequency of attendance at the practice in the previous year were not found to be useful markers for targeting screening efforts. Although it is potentially beneficial for detecting unmet need, home-based screening is resource-intensive and requires further examination in randomized trials in the North American context.

Hypertension in the elderly

The elderly differ biologically from young and middle-aged adults. We cannot assume that hypertension has the same significance in the elderly or that treatment outcomes will be similar. Evidence concerning the risks of hypertension and benefits of antihypertensive therapy in the elderly is reviewed and the implications for patient management are outlined. There are hazards to antihypertensive therapy; an approach to treatment is presented.

Pressure sores: an age-old problem of the aged

The most frequently cited and/or best-designed studies of pressure sore prevention and treatment in the last 25 years are almost all uncontrolled. These studies are critically reviewed. An appropriate methodology for evaluating the effectiveness of decubitus ulcer management, based on data and experience, is outlined. A suggested treatment protocol is described.

Resolving the sore throat dilemma

Many physicians ignore the traditional dictum that throat culture is the only tool of value in assessing sore throat. A review of the literature supports this skepticism. Evidence indicates that clinical assessment has been underestimated and the significance of positive culture exaggerated.An approach to managing pharyngitis utilizing the combined strengths of throat culture and clinical assessment is proposed. This approach avoids needless cultures, minimizes unnecessary antibiotic use, achieves prompt clinical improvement in patients whose symptoms are most severe and reduces the risk of long term morbidity from rheumatic heart disease to negligible levels.

Constipation in the elderly

Constipation is common in the elderly, although apparently no more so than in the general population. Constipation is not a consequence of normal aging. The definition and causes of constipation are discussed. A common-sense approach to investigation at the primary care level is outlined. Available laxative preparations are reviewed. A step-wise approach to the treatment of chronic constipation includes ensuring adequate fluid intake, maximizing activity and providing adequate bulk. A program of bowel training for use in resistant cases is described. Use of oral laxatives is de-emphasized.