The psychological consequences of predictive testing for Huntington's disease. Canadian Collaborative Study of Predictive Testing

BACKGROUND

Advances in molecular genetics have led to the development of tests that can predict the risk of inheriting the genes for several adult-onset diseases. However, the psychological consequences of such testing are not well understood.

METHODS

The 135 participants in the Canadian program of genetic testing to predict the risk of Huntington's disease were followed prospectively in three groups according to their test results: the increased-risk group (37 participants), the decreased-risk group (58 participants), and the group with no change in risk (the no-change group) (40 participants). All the participants received counseling before and after testing. Standard measures of psychological distress (the General Severity Index of the Symptom Check List 90-R), depression (the Beck Depression Inventory), and well-being (the General Well-Being Scale) were administered before genetic testing and again at intervals of 7 to 10 days, 6 months, and 12 months after the participants received their test results.

RESULTS

At each follow-up assessment, the decreased-risk group had lower scores for distress than before testing (P < 0.001). The increased-risk group showed no significant change from base line on any follow-up measure, but over the year of study there were small linear declines (P < 0.023) for distress and depression. The no-change group had scores lower than at base line on the index of general well-being at each follow-up (P < or = 0.045). At the 12-month follow-up, both the increased-risk group and the decreased-risk group had lower scores for depression and higher scores for well-being than the no-change group (P < or = 0.049).

CONCLUSIONS

Predictive testing for Huntington's disease has potential benefits for the psychological health of persons who receive results that indicate either an increase or a decrease in the risk of inheriting the gene for the disease.

The merits of confidence intervals relative to hypothesis testing

A variety of statistical tests of a null hypothesis commonly are used in biomedical studies. While these tests are the mainstay for justifying inferences drawn from data, they have important limitations. This report discusses the relative merits of two different approaches to data analysis and display, and recommends the use of confidence intervals rather than classic hypothesis testing.

Formulae for a confidence interval surrounding the point estimate of an average value take the form: d= ±zσ/√n, where “d” represents the average difference between central and extreme values, “z” is derived from the density function of a known distribution, and “a/-∨n” represents the magnitude of sampling variability. Transposition of terms yields the familiar formula for hypothesis testing of normally distributed data (without applying the finite population correction factor): z = d/(σ/√n).

Utilization management: a literature review for Canadian health care administrators

Utilization management (UM), the attempt to measure, understand and reduce inappropriate hospital use, has been in development for over 20 years. It is an outgrowth of two related phenomena: (1) the increasing responsibility of large institutional third party payers for health care costs and the increasing demand of those payers for accountability; and (2) in Canada, particularly, the debate surrounding the adequacy of hospital funding and the perceived inadequacy of cost control using global budgeting. Given the interest in UM, hospital administrators, provincial and federal associations representing hospitals, hospital employees and physicians would find a review of UM programs useful in terms of what is known about their effectiveness, and the specific initiatives in Canada. The authors underscore the critical need for formal evaluation of UM programs; to date there has been little systematic research into issues related to its implementation and impact. This issue is particularly pertinent because UM programs have not been widely implemented in Canada.

Anemia in pediatric day-surgery patients: prevalence and detection

A prospective study was conducted to determine the prevalence of anemia in pediatric day-surgery patients, and a single-blinded study was conducted to evaluate the anesthesiologist's capability to detect preoperative anemia clinically. The subsequent management of children with anemia was noted. During the preoperative examination the anesthesiologist completed a questionnaire and predicted the preoperative hemoglobin concentration based on the history and physical examination. The preoperative hemoglobin concentration was measured for all of the patients, but the results were withheld until after completion of the questionnaire. Documentation was complete in 2,649 patients, and these comprised the final study group. Fourteen patients (0.5%) were anemic (hemoglobin concentration less than 100 g/l), but of these, only 5 had been predicted to be anemic based on clinical examination. Seven of these 14 anemic patients were less than 1 yr of age. Only 2 of the anemic patients had surgery postponed, and 1 of these also had a respiratory infection. Forty-four patients were incorrectly predicted to be anemic (i.e., their actual hemoglobin concentration was greater than 100 g/l). We conclude that in our patients, anemia is rare but is more likely to occur in those less than 1 yr of age. The presence of mild degrees of anemia does not alter the decision to proceed with day surgery. The anesthesiologists participating in this study could not reliably detect anemia clinically.

Hospital-based utilization management: a cross-Canada survey

Utilization management attempts to measure, understand and, when appropriate, reduce hospital use. We conducted a telephone survey to determine the status of utilization management in Canadian hospitals. The sample comprised a random selection of 30% of acute-care hospitals with over 100 beds for adults in Ontario and Quebec and all such hospitals in the other provinces. Of the 123 chief executive officers contacted 99 (80%) claimed to have a utilization management program. Of those, 90 (91%) agreed to participate in an in-depth survey or to designate a senior administrator to be interviewed who was most knowledgeable about the program. High occupancy rates and funding issues were the most common environmental triggers for the development of utilization management programs; funding issues were listed more frequently by respondents in Ontario than by those elsewhere (p = 0.0008). Retrospective review alone was used in half of the hospitals, concurrent review or some mixed approach being used in the other half. Ontario and the Atlantic provinces were more reliant than the rest of the country on retrospective review alone (p = 0.0032). Most of the hospitals used peer review and education to stimulate corrective action. Of the respondents 67% indicated that the medical staff supported the utilization management program, and 53% reported that the program had a positive impact on the relationship between administrative and medical staff. Most of the respondents were unsure of the program's impact on the quality of care or the rate of unnecessary hospital admission. However, retrospective review alone was found to be less successful in reducing inappropriate utilization than either concurrent review or combined review (p = 0.0048).

Retinopathy of prematurity-induced blindness: birth weight-specific survival and the new epidemic

A recent population-based study in the Canadian province of British Columbia showed that, since the mid-1960s, there has been a significant increase in the incidence of retinopathy of prematurity-induced blindness in infants weighing 750 to 999 g at birth. To determine the impact of changing birth weight-specific survival on this new epidemic, all infants born in the province in the period 1952 through 1986 and known to the British Columbia Health Surveillance Registry as having retinopathy of prematurity-induced blindness were identified. In addition, the birth registration records for the 1,299 740 infants born in British Columbia in the same period and the death records of the 22,940 British Columbia-born infants who died in the province before the end of their first year of life were linked using a combination of probabilistic and manual record linkage techniques. These linked records and the records from the Health Surveillance Registry were used to calculate birth weight-specific incidence rates of retinopathy of prematurity-induced blindness in liveborn infants and first-year-of-life survivors. The rates, in 5-year intervals, showed that, in both liveborn infants and first-year survivors, the highest birth weight-specific rates occurred during the first epidemic of retinopathy of prematurity, which ended in British Columbia in 1954. Since the mid-to late-1960s, the incidence of retinopathy of prematurity-induced blindness in liveborn infants weighing less than 1000 g increased steadily whereas in infants weighting 1000 to 1499 g, incidence decreased slightly since the original epidemic ended. However, the experience of first-year-of-life survivors is substantially different.(ABSTRACT TRUNCATED AT 250 WORDS)

Episiotomy in low-risk deliveries: physician factors

From 376 randomly selected nulliparous women who delivered at the Grace Hospital in 1986, we selected 133 low-risk women and performed a retrospective chart review to ascertain the episiotomy rate for physicians by sex, years since graduation, and specialty status. There was a statistically significant difference between the rate for specialists (65%) and general practitioners (38%). A non-significant difference was found between male physicians (41%) and female physicians (56%) and between physicians who had graduated within 15 years (42%) and those who graduated more than 15 years ago (52%). Subgroup analysis of the general practitioner data revealed different patterns for male and female physicians according to their graduation cohort.

A trial of desmopressin (1-desamino-8-D-arginine vasopressin) to reduce blood loss in uncomplicated cardiac surgery

Previous studies have suggested that desmopressin may reduce the bleeding diathesis that often complicates open-heart surgery. To pursue this question further, we performed a double-blind, randomized, placebo-controlled trial to determine whether the previously reported beneficial effect of desmopressin on hemostasis during complex cardiac surgery was applicable to all elective cardiac surgical procedures involving cardiopulmonary bypass. In 150 consecutive patients, most of whom underwent primary coronary-artery bypass grafting, we compared the effects of intravenous desmopressin (0.3 microgram per kilogram of body weight) with those of saline placebo on postoperative blood loss and the need to replace blood products. The median amount of blood lost within the first 24 hours after operation was similar in the desmopressin and placebo groups (865 vs. 738 ml; P = 0.26). The postoperative use of blood replacement products did not differ significantly between the groups (1025 ml [95 percent confidence interval, 300 to 4140 ml] in the desmopressin group and 860 ml [247 to 5346 ml] in the placebo group). Desmopressin is believed to exert its hemostatic effect by releasing von Willebrand factor. The level of ristocetin cofactor, a functional index of the level of von Willebrand factor, was increased approximately twofold from base line in both treatment groups 90 minutes and 24 hours after the administration of medication. Similarly, the levels of von Willebrand factor multimers increased uniformly in both groups. These findings may be consistent with a normal stress response of von Willebrand factor to major surgery and could explain our failure to detect a therapeutic effect of desmopressin. We conclude that the majority of patients who undergo elective cardiac surgery receive no hemostatic benefit from the use of desmopressin.

Randomized, double-blind, controlled trial of long-term diuretic therapy for bronchopulmonary dysplasia

The effects of continuous therapy with hydrochlorothiazide and spironolactone on pulmonary function in 34 premature infants with severe bronchopulmonary dysplasia were assessed in a randomized double-blind controlled trial. Subjects were greater than or equal to 30 days old, were supported by mechanical ventilation in greater than or equal to 30% oxygen, and had radiographic evidence of bronchopulmonary dysplasia. The treatment group (n = 19) and the placebo group (n = 15) were similar in all respects except for distribution of gender. Anthropometrics, ventilatory measurements, and the results of pulmonary function tests were evaluated at study entry and at 1, 4, and 8 weeks into therapy. Poststudy chest radiographs were compared with those obtained before the study. The proportion of infants alive at discharge was significantly increased (84%) in the treatment group compared with the placebo group (47%) (p = 0.05). There were no statistically significant differences in total hospital days or in total ventilator days. Total respiratory system compliance at 4 weeks was higher in the treatment group (0.61 +/- 0.18) than in the placebo group (0.45 +/- 0.13) (p = 0.016). No difference in outcome was detected between male and female infants in the treatment group. These results suggest that long-term diuretic therapy improves outcome in infants with bronchopulmonary dysplasia.

A comparison of photoscreening techniques for amblyogenic factors in children

We screened 236 consecutive patients aged 6 years or less using an Off-Axis photoscreener and an Otago-type photoscreener. With a masked standardized clinical assessment as the standard, an overall comparison of the results obtained with the two techniques revealed a sensitivity and specificity in the neighbourhood of 0.85 and 0.87 respectively for the Off-Axis photoscreener and 0.94 and 0.94 respectively for the Otago photoscreener. Both techniques, but especially the Off-Axis technique, were less sensitive and specific in younger children (24 months or less). Fundus colour (light or dark) did not greatly affect sensitivity or specificity. Photoscreening with the pupil dilated led to an increase in false-positive results with both techniques. Our results showed the Otago photoscreener to be superior in this clinical trial.

Practice patterns of family physicians with 2-year residency v. 1-year internship training: do both roads lead to Rome?

Are there differences in patterns of practice between actively practising physicians who have been certified after a 2-year family practice residency and matched physicians without certification who have completed the standard 1-year internship? With the use of billing files prepared by the British Columbia Medical Association a group of 65 family practice certificants in active practice in British Columbia was compared with a control group of 130 internship trainees matched by year and school of graduation, category of billing (i.e., solo or group) and region. A wide range of practice features was assessed for the fiscal years 1984-85, 1985-86 and 1986-87. No differences were detected between the groups in 1986-87 for the following practice variables: number of patients (1888 and 1842 respectively), number of personal services billed for (7265 and 7173), number of personal services per patient (3.9), amount of funding for personal services ($140,192 and $140,100) and amount per patient for personal services ($77 and $79). Age-adjusted costs for male and female patients were similar in the two groups. Of six services thought to be influenced by type of training, only maternity care generated a significantly higher number of billings in the study group (341 v. 249). These results suggest that there is no demonstrable effect of training on patterns of practice. However, the question of the effect of training on quality of care and whether the 2-year residency may have a longer effect on practice patterns should be the focus of future research.

Retinopathy of prematurity: a new epidemic?

This study provides the first empiric evidence for the existence of a new epidemic of retinopathy of prematurity-induced blindness. Data from a population-based register of handicapping conditions in the Canadian province of British Columbia, and a birth weight-specific census of live-born infants in British Columbia, were used to determine annual, population-level incidences of retinopathy of prematurity-induced blindness during 1952 to 1983. Changes in incidence since the end of the original epidemic (1954) were determined by subdividing the 29-year period (1955 to 1983) into two intervals (1955 to 1964 and 1965 to 1983). Standardized incidence ratio analyses revealed a marginally significant increase in the overall incidence of retinopathy of prematurity-induced blindness in the later as compared with the earlier period. Infants weighing 750 to 999 g at birth had a significantly increased standardized incidence ratio of 3.07 (95% confidence interval 1.26, 11.06). No increases in risk were observed in heavier or lighter weight infants. Because ascertainment and diagnostic changes do not explain the weight-specific increases in incidence, these results provide the first population-level evidence for a new epidemic.

Evaluation of a postocclusive reactive circulatory hyperaemia (PORCH) test for the assessment of ulnar collateral circulation

This prospective double-blind study compared Doppler assessment of the ulnar collateral circulation with the Allen's test and a postocclusive reactive circulatory hyperaemia (PORCH) test in 144 patients (288 hands). The PORCH test involves inflation of a blood pressure cuff on the upper arm to a supra systolic (+50 mmHg) pressure for two minutes. Prior to cuff deflation, both radial and ulnar arteries are occluded at the wrist; the cuff is then deflated and a 15-second period allowed so as to restore blood flow down to the wrist. Ulnar artery compression is now released and the time to revascularization measured. Fifty-eight per cent of hands with an abnormal Allen's test had a normal ulnar collateral circulation. Results of Allen's test were not significantly affected by patients' sex or smoking status (p greater than 0.1) but there was a significant difference (p = 0.001) in the false positive rates between patients over 40 years of age (0.2) and those under 40 years of age (0.03). Results of the PORCH test were not significantly affected by patients' age, sex or smoking status (p greater than 0.1). With a revascularisation time of 19 sec as a "cut off" for ulnar abnormality the PORCH test, unlike the Allen's test, was perfectly predictive of an abnormal ulnar collateral circulation and had no false positives.

The assessment of diagnostic tests: a comparison of medical literature in 1982 and 1985

To determine whether improvements have occurred since a survey of the 1982 literature assessing diagnostic tests, the authors evaluated all English-language articles that assessed clinical diagnostic tests in abridged Index Medicus journals in 1985, and that had the terms sensitivity and specificity in the title, abstract, or key words. The 89 articles were assessed against seven methodologic criteria, including use of a well-defined "gold standard," clearly defined test interpretation, blinding, clear data presentation, correct use of sensitivity and specificity, calculation of predictive values, and consideration of prevalence. In comparisons of 1985 vs. 1982 articles, there were significant improvements in five of the seven criteria. For example, the proportion of articles using a well-defined "gold standard" rose from 68% to 88%. Overall, the frequency of papers demonstrating five or more of the seven criteria increased from 26% to 47%. However, predictive values were discussed in only 54% of the articles without, necessarily, consideration of the influence of prevalence as well. This study raises the concern that while the concepts of sensitivity and specificity are now accepted, predictive values remain less well understood. Although there has been an improvement in the assessment of diagnostic tests in published research, attention to accepted methodologic standards is still needed on the part of researchers, reviewers, and editors.

Prenatal care: a comparative evaluation of nurse-midwives and family physicians

We evaluated the prenatal care provided to 44 low-risk women by nurse-midwives (NMs) at a special clinic of a large obstetric referral hospital and a sample of 88 low-risk women attended by family physicians (FPs) in their offices. The women were matched on the basis of date of delivery, age, parity, number of previous miscarriages, gravidity, socioeconomic status and delivery after 32 weeks' gestation. The Burlington Randomized Controlled Trial criteria, which reflect community standards of care, were updated and used to assess the information, which was provided on standard provincial prenatal care forms. Scoring was carried out blindly, and interrater reliability was high. A highly significant difference was found in the proportions of NM and FP charts that were rated adequate, superior or inadequate: 77% v. 24%, 7% v. 16% and 16% v. 60% respectively. The rate at which procedures were omitted (leading to an inadequate score) in the categories of initial assessment, monitoring and management also varied between the two patient groups. These findings, even when considered in terms of several biases that may have resulted in the high proportion of NM charts rated at least adequate, suggest that NMs provide prenatal care to low-risk women that is comparable, if not superior, to the care provided by FPs.

The epidemiology of school injuries: the problem of measuring injury severity

In the few surveys of injuries occurring in schools, severity has been defined using a priori criteria based on the nature of injury and by the area injured. The validity of these methods of classifying injury severity has not been established. The association between two commonly used measures of injury severity (nature of injury and body area injured) with referral to medical assessment was explored, based on a simple model derived from the literature. Kendalls Tau-b was used to assess the association between the indicators of injury severity and referral; controlled for both school level (elementary school and secondary school) and the degree of behavioural control that could be exerted in the location of the injury. There was a very low association between indices of injury severity and referral for medical assessment regardless of level of school or degree of behavioural control. It is concluded that the simple model derived from the literature does not adequately describe the relationship between injury severity and referral in the school setting. The major issue facing school staff is not the measurement of injury severity per se, but the appropriate referral of the injured child for medical assessment and treatment.

Prison health services: a utilization study

A prospective study of health service utilization carried out in the Correctional Services of Canada (CSC), Pacific Region, is reported. Health service encounters occurring at the six Regional Institutions with on-site health care centers between May 29th and June 28th, 1984 were surveyed using a health clinic encounter form. There were 7,449 encounters during the study period. The mean rate of encounters was 5.2 per inmate. Seventy-two percent of these encounters occurred at wickets, and 28% occurred at clinics. Physician visits occurred at a mean estimated annual rate of 6.7 visits per year. This is 2.4 times higher than the mean annual physician visit rate for non-institutionalized men in Canada. The reason for visits was new illness (57%), chronic illness (31%), injuries (5%), psychosocial problems (2%), and administrative (5%). The encounter rate per 100 inmates varied from 19.7 to 1,203.6 across the institutions studied. Overall 89% of all visits were seen by health service nurses, while 11% were seen by physicians. Using ICHPPC-2 Defined, the ten most common complaints presented to the health service were headache, sore throat, stomach complaint, other respiratory complaint, tension headache, limb pain, other/not codable, medical examination, back pain and upper respiratory tract infection. These ten complaints accounted for 4896 (59%) of the total complaints recorded. The majority of visits took less than five minutes, were most often treated with medication, and did not require scheduled follow-up. The 50 most frequent visitors, those making 25 or more visits during the study period, while only 3.5% of the study population, accounted for 25% of all encounters.

Epidemiology of school injuries: a 2-year experience in a municipal health department

School injuries occurring in a municipal school system during a 2-year period were reviewed to identify epidemiologic features of school injuries, to determine data requirements for ongoing injury surveillance, and to identify potential preventive strategies. Overall, 3,009 injuries were reported (2.82/100 students per year). Elementary school students had only a slightly higher rate (2.85) than secondary school students (2.78). However, the cause, nature, school location of injury, and body area injured formed distinct patterns in these two groups. Playgrounds were responsible for the highest overall and elementary school rates, whereas sports areas and classrooms had the highest rates among secondary school students. Falls were the most frequent cause of injury in elementary schools whereas, as expected, sports injuries were the most frequent cause among secondary school students. Contusions and abrasions of the head were the most frequent type of injury for both groups, although more common among elementary school students, whereas fractures, sprains, strains, and dislocations were more frequent among secondary school students. Although the proportion of severe injuries to secondary school students was slightly higher (39 v 35%), the rate of referral of students to a hospital or physicians among secondary school students (1.21 per 100 student-hours) was almost twice the rate of elementary school students (0.65 per 100 student-hours). Problems with definition of injury severity and the need to explore the social aspects of schools as a factor in injuries emerged as important considerations for future research.