Case-finding Methods Research Articles

Telephone Screening for Risk of HIV Infection

This study responds to a Centers for Disease Control request to develop innovative case-finding methods and asks two questions: 1) Will men participate in an anonymous telephone interview containing detailed questions about their sexual practices to enable screening for HIV-related risk? 2) Will individuals told they are at increased risk follow up by calling a toll-free number for additional AIDS information, counseling, or medical evaluation? Random-digit-dialed interviews were completed with 1610 adult men in Los Angeles County; the completion rate among eligible men was 68.3%. Nearly 43% of men were assessed at increased risk, half of whom described behaviors that placed them only at moderate risk and half of whom reported behaviors placing them at higher risk. Although the study found men were willing to provide personal risk-assessment information, only 14 of 343 men were willing to initiate a follow-up telephone call to the project counselors as the next step in case-finding.

Prevalence of Alzheimer's Disease-Reply

In Reply.— Our erroneous citation of the review by Rocca et al 1 was based on an incorrect interpretation of the data presented in Table 2 of that work. Dr Prohovnik and other readers should be cautious about direct comparisons of Alzheimer's disease prevalence estimates from various studies. As noted in our report, these studies differ substantially in methods, especially in the degree to which they are limited to severe disease and in completeness of case finding methods. The East Boston study has advantages in this regard because it included all levels of disease severity and because participants were sampled from all levels of performance on the population screening test. These features led to estimates of Alzheimer's disease prevalence that are more complete than those from most previous studies.

The prevalence of PSE-CATEGO disorders in a Finnish adult population cohort

A normal Finnish population cohort, originally aged 15-64 years, has been followed psychiatrically for 16 years. In the 16-year follow-up, 742 of the original sample of 1000 persons could be contacted and personally examined i.a. by means of the full 140-item version of the PSE. The age-adjusted prevalence of mental disorders in the population aged 30-80 years was 9.9% (6.9% in men and 12.4% in women). The prevalence of psychotic conditions was exceptionally high in comparison to other studies, 2.7%. The occurrence of mental disorders was associated with marital status and social class in men but not in women. Other factors examined, namely age, education, occupational category and experience of unemployment during the follow-up period, were not associated with the occurrence of mental disorders. The results are compared with the results from other studies using the same case finding method.

The Epidemiology of Primary Biliary Cirrhosis in North-east England: an Increasingly Common Disease?

The reported incidence and prevalence of primary biliary cirrhosis has risen in the past 10 years in Northern Europe. In order to determine whether this is a genuine increase in the disease or an apparent increase due to increased awareness of physicians and more ready diagnosis, we have carried out a comprehensive epidemiological study of primary biliary cirrhosis. All possible cases from 1965-1987 were examined using the best case finding methods available. In a relatively stable population of about 1.92 million we identified 471 patients with 'possible' primary biliary cirrhosis and 347 with a definite, histologically confirmed, diagnosis. Prevalence rose from 18/1,000,000 in 1976 to 128.5/1,000,000 in 1987 (276/1,000,000 in women greater than 18 years). Increased awareness and availability of interested physicians seemed to be important contributing factors to the rise in prevalence. No important geographical clustering of cases was noted.

Distinguishing Depression From Functional Impairment in the Medical Outcomes Study-Reply

In Reply.— Dr Jencks raises important issues regarding (1) the overlap of symptoms of depression with functional status, (2) comparison of patients with depressive symptoms above a specific threshold with medically ill patients without confirmed current symptoms, and (3) differences in case-finding methods. In response, we first discuss the nature of the conditions studied and then comment on each issue. Depression is a condition that is only defined when some symptoms are present; there is no truly asymptomatic depression. Thus, to study the morbidity associated with depression, one must identify persons who are actively depressed. Chronic medical conditions, however, are thought to be ongoing, nonreversible, pathological processes with varying symptom presentation. For such conditions, it makes sense to examine morbidity at any phase of the illness; a study based on only symptomatic cases of hypertension, for example, would not be particularly representative of patients with hypertension. As we noted in

Lifetime prevalence of cognitive impairment by Chinese-modified NIMH diagnostic interview schedule among the elderly in Taiwan communities

Lifetime prevalence of cognitive impairment by Chinese-Modified NIMH Diagnostic Interview Schedule (DIS-CM) among the community population aged 65 and over in Taipei City, 2 townships and rural villages, are: 2.8%, 12.9% and 12.9% for definitely mild ; 1.6%, 9.0% and 5.4% for definitely mild and possibly severe; and 1.3%, 9.6% and 1.8% for definitely severe cases, respectively. The prevalences increase with age in both sexes. In general, prevalence rates are higher in females than males with some inconsistent differences between severity of impairment and age-groups in each of three sites. High rates of errors in and/or refusal of three specific questions in both cases and noncases are noteworthy. Whether this indicates the limitations of the DIS-CM in case-identification of cognitive impairment in the elderly in Chinese community population deserves further study. The lower rate of severe cognitive impairment among the elderly in urban than that in rural areas as indicated in this study is in accord with the NIMH ECA Studies which adopted the similar case-finding method, and also with two recent studies in Taiwan which used the different case-identification method.

Increasing incidence of multiple sclerosis in South Lower Saxony, Germany.

In the epidemiological area of South Lower Saxony the prevalence of multiple sclerosis increased from 51/100,000 in 1969 to 99 in 1986. The mean annual incidence increased from 2.6 for the period from 1964-1974 to 4.6 for 1975-1985. This trend is significant (p = 0.0068). Diagnostic criteria, methods of case finding and analysis of the data remained stable. Minor necessary changes as for example due to new data protection laws and new handling of early cases by practising physicians can hardly explain this significant increase. In consideration of similar reports from all over the world biological exogenous factors are suspected but remain to be identified.

Automedicación y cumplimiento farmacológico en una consulta de atención primaria

The prevalence of reported self-medication and compliance and some associated factors in patients 25 and over years of age attending a primary health center is studied using the case finding method, during the period of March-December, 1987. Self-medication was reported by 48% of patients (41% were taking one drug and 7% two drugs). Nervous system drugs were the most common pharmacologic group over the counter. As for compliance of prescribed drugs, 81% reported to take their medication in the prescribed way at least 3 out of 4 times. Younger patients reported more self-medication. Non compliance was more frequent in members of larger families. No other statistical differences were found. We conclude that the patients in our practice report a high level of self-medication and also a high level of compliance of prescribed drugs. These data are to be taken into account for the planning of future health programs targeted to the use of drugs in our community.

A study of the use of maternity and child welfare clinics in case-finding for pulmonary tuberculosis in KENYA

This investigation is the seventh in a series of case-finding studies in Kenya. It explores the potential value of questioning mothers attending maternity and child welfare (M & CW) clinics to identify tuberculosis suspects (individuals aged 6 years or more with a cough for 1 month or more or hemoptysis) living in their households. The study was carried out in all the eight M & CW clinics in two divisions (populations 86 000 and 112 000) of two different districts. The mothers were asked to give a standard letter, which explained the possible importance of a chronic cough, to each suspect they identified and invited the suspect to attend the district hospital chest clinic. Each suspect attending the clinic was entered in a special register and two sputum specimens were collected. For those who failed to attend, the specimens were collected at a home visit. Of the total of 342 suspects living in the two study areas who were registered at the M & CW clinics during 1 year, 261 were identified by the mothers but 19 denied having received the standard letter. The remaining 81 had not been identified by mothers but had attended the M & CW clinics on their own initiative. Of the 242 suspects who received the letter, 89 (39 %) attended the hospital chest clinic, 74 % within a week of the letter being issued from the M & CW clinic. The main reasons given for not attending the hospital chest clinic by the remaining suspects were financial or because their cough had improved or disappeared. Sputum was collected from 238 suspects and examined bacteriologically: in six (2.5 %) it was positive for tubercle bacilli on smear and culture and in a further two (0.8 %) the sputum was positive on culture only. Of those attending the hospital chest clinic 2.9 % were smear- and culture-positive and 4.7 % were culture positive. This method of case-finding has yielded disappointing results, for only 4 % of the estimated annual incidence of smear-positive cases was detected.

Controversies in Screening for Middle Ear Disease and Hearing Loss in Children

GOALS —Charles D. Bluestone, MD, and Thomas J. Fria, PhD The goal of this Workshop was to assemble experts in pediatrics, infectious disease, otolaryngology, epidemiology, audiology, and biostatistics to assess the current status of screening for otitis media in infants and children. The need for such a Workshop has become increasingly apparent with the advent of the widespread use of tympanometry as a case-finding method and the controversies that have surrounded these proliferating screening programs. Specifically, the objectives of the Workshop were to (1) review the state of our knowledge of middle ear disease in children in terms of its epidemiology, diagnosis, management, complications, and sequelae, all of which pertain to the justification for screening; (2) review the epidemiologic basis of screening and relate these to otitis media; (3) review current viewpoints on screening for middle ear disease from professionals in the field; (4) review the current status of screening programs in the United States; (5) attempt to reach concensus as to the target population to be identified by screening and the most appropriate and reasonable method for screening and referral; and, (6) make recommendations as to the best manner in which to resolve the remaining controversial issues. In addition to the above named specialists, representatives from federal funding agencies and from screening instrument companies were present in an ex officio capacity. A summary of the discussions is presented here. INCIDENCE, PREVALENCE, AND NATURAL HISTORY OF OTITIS MEDIA —Margaretha L. Casselbrant, MD Otitis media is one of the most common diseases of childhood and, thus, has important economic and health care implications in society.

Assessment of laboratory methods for detection of unsuspected diabetes in primary health care.

In order to assess different methods for early detection of unsuspected diabetes, urine and venous blood samples were collected at random from 1082 patients visiting a primary health care centre in southern Sweden. Blood glucose was analysed by the hexokinase method along with the Dextrostix-Eyetone reflectance meter. Urine glucose was determined by Clinistix, Diastix, Neostix, Rediatest, Clinitest and quantitatively by the hexokinase method. Patients fulfilling the criteria of a positive screen were subjected to a diagnostic investigation with an oral glucose tolerance test. Out of 89 positive screenees, 37 patients were classified as diabetics, showing a prevalence of diabetes in the study population of 3.4% according to the WHO criteria. Impaired glucose tolerance was found in 14 patients. In a control group of 56 patients, randomly selected among negative screenees, no cases of diabetes were found. Random blood glucose measurement by the hexokinase method, using 7 mmol/l as a screening level, had a significantly higher sensitivity (95%) than all urine glucose methods (59-30%) with comparable specificity (97-99%). Use of the Dextrostix-Eyetone reflectance meter resulted in a decrease in sensitivity to 75% without any change in specificity or predictability, compared with the hexokinase method. Urine testing for glucose was found to be a suboptimal method for early case finding of diabetes among patients receiving primary health care.

Targeting services to chronically disabled elderly: the preliminary experiences of the National Long Term Care Channeling Demonstration.

In response to concerns about the adequate provision of long term care, the National Long Term Care Channeling Demonstration has been funded by the Department of Health and Human Services. The project is designed to provide coordinated community services as an alternative to institutionalization to those elderly individuals at risk of placement. This preliminary work examines the demonstration's experience in its attempt to target services to these individuals. Although final research results are not yet available, the method, problems, and results of the initial case finding and screening approaches provide additional knowledge concerning the targeting experience.

Etiology of Ventricular Septal Defects: An Epidemiologic Approach

To investigate the recent 150% increase in the reported incidence of ventricular septal defects (VSDs) in the United States, the epidemiology of ventricular septal defects was examined. The apparent incidence of VSDs is highly dependent on case finding methods, and more complete diagnosis and reporting probably account for the increase in reported incidence. Variations in case ascertainment also account for the small differences in incidence in studies from different places. The several known risk factors for VSD, including a family history of congenital heart disease and exposure to certain drugs, infectious agents, and maternal metabolic disturbances, explain few cases. Incidence rates are similar in different races and seasons and are unrelated to maternal age, birth order, sex, and socioeconomic status. VSDs occur naturally in a wide range of mammals and in birds, which also have four-chambered hearts. Despite identical genes and similar prenatal environments, the concordance rate in identical twins is only about 10%. The consistency of incidence among individuals with widely differing genes and environments and the frequency of discordance in identical twins suggest that VSDs often occur as random errors in development, at a frequency largely determined by the complexity of normal cardiac morphogenesis. This hypothesis has two major implications: many VSDs are not preventable and parents need not feel responsible for VSDs in their children.

Epilepsy after a first unprovoked seizure in childhood.

One hundred sixty-eight children with an initial afebrile, unprovoked seizure were identified from a regional EEG laboratory. This case-finding method seemed justified because 86% of regional physicians indicated they order an EEG after a first seizure. Clinical information and recurrence rate were determined from records and telephone calls. Eighty-one percent had been seen by a pediatric neurologist. Overall, 51.8% recurred, and of those with a recurrence, 79% had additional seizures. Recurrence rates were highest in those with abnormal neurologic examination, focal spikes on EEG, and complex partial seizures. The lowest rates of recurrence followed a generalized tonic-clonic seizure, with normal EEG and normal neurologic examination. Prescription of anticonvulsants did not alter the recurrence rate.

Radioactive Fallout and Cancer

To the Editor.— The study by Dr Carl Johnson 1 quoted our work out of context 2 to support the accuracy of his method of identifying cancer cases among those exposed to radioactive fallout. Johnson used community volunteers to interview self-selected heads of families to ascertain each cancer in family members over the preceding 30 years. The interview was conducted after the families had viewed an antinuclear television documentary entitled "Paul Jacobs and the Nuclear Gang," which strongly suggested that fallout had caused cancers in persons living downwind ( Salt Lake Tribune , Aug 30, 1981, p A17). Johnson cited us to support the accuracy of his case-finding method to the effect that "diagnosis in life correlated with death certificate cause and with unpublished data from the Utah Cancer Registry more than 90% of the time." This is taken out of context. The full quote reads, " The cases of leukemia included in this

Study of case-finding for pulmonary tuberculosis in outpatients complaining of a chronic cough at a district hospital in Kenya.

This investigation is the fifth in a series of case-finding studies in Kenya. It explores the potential for case-finding by the identification of persons with suspected tuberculosis (persons with a cough for 1 month or more) through careful screening of general outpatients attending a district hospital. Of 601 suspects identified among 20,756 new outpatients attending hospital during a period of 11 wk, 5.6% were considered by an independent assessor to have active pulmonary tuberculosis (2.2% with sputum positive on both smear and culture, 1.2% on culture only, and 2.2% negative sputum but radiographically active lesions). A further 2.0% were considered to have inactive tuberculosis. This method of case-finding appears to be uniformly effective within a radius of approximately 9 miles of the hospital, becoming less effective outside this range. There were certain important diagnostic pointers. There was an excess of tuberculosis cases in males, in those with weight loss, in those with a history of cough of less than a year, in those with a history of hemoptysis, and in those 35 yr of age or older. This investigation provides additional support to our previous studies, which demonstrated serious problems of case-finding in the peripheral health units and suggests that unless the infrastructure of primary health care at the periphery can be improved, the policy should be to diagnose tuberculosis in the district hospital and to operate a simple referral system for persons with suspected tuberculosis from the periphery.

Some observations on poliomyelitis lameness surveys.

Since 1974, greater than 100 different surveys have been carried out throughout the developing world to estimate the prevalence of lameness due to poliomyelitis. Reported prevalence rates have ranged from less than 1 to a high of 25 per 1,000 children surveyed and have prompted many countries to undertake polio vaccination programs. A review of surveys conducted to date reveals considerable variation in both the choice and use of survey methods and in the assumptions made in the analysis and interpretation of findings. More precise and comparable data about the risk of poliomyelitis could be obtained in future surveys by incorporating a standard case definition, by using house-to-house case-finding methods in representative community-based samples, by analyzing and presenting rates in more clearly defined ways, and by selecting stable populations for study.

A novel method of assessing completeness of tumor registration.

A random sampling method of measuring the completeness of registration of cancer patients was tested at a university referral hospital. The target population consisted of all inpatients and nonprivate outpatients with in situ or invasive malignancies. The medical records of a random sample of all hospital records active in the last five years were reviewed to determine their reportability and inclusion in the tumor registry (Method A). Traditional casefinding assessment methods were also employed by conducting a complete review of four commonly used hospital sources for a short time period (Method B). The primary purpose of the study was methodologic; namely, to test the feasibility of Method A and to characterize it relative to the more traditional Method B. The estimated missed case rates using Methods A and B (3% and 5%, respectively) are not directly comparable because not all outpatient information is recorded in the medical record. It is concluded that as a means of completeness assessment, Method A can be feasible, cost effective, and useful in other institutions provided certain conditions are met: (1) an appropriate random sample of the target population can be obtained; (2) all relevant information is available in a unit medical record; (3) the reviewer is fully aware of the reportability criteria.

A fourth study of case-finding methods for pulmonary tuberculosis in Kenya

This investigation is the fourth of a series of case-finding studies in Kenya. It explored in a new area (the Baragwi location of Kirinyaga), five methods of case-finding involving the examination of the sputum by smear and culture of symptomatic tuberculosis suspects in the community identified (i) by interrogation of the Elders, (ii) by interrogation of household heads, (iii) by tracing all patients registered during the previous 10 years in the District Tuberculosis Register, (iv) by the examination of all their close contacts and (v) from outpatients attending peripheral health units. The initial interrogation of the Elders yielded 123 suspects with bacteriological results, of whom seven were culture-positive, including four smear-positive. A second interrogation three to six months later produced a further 66 suspects and four more culture-positive cases (all smear-negative). The examination of a second sputum specimen after three to six months from all the suspects from both interrogations produced a further culture-positive smear-negative case. A single interrogation of household heads in a house-to-house survey yielded 867 suspects and 15 culture-positive cases, including eight smear-positive. Of 862 suspects with no history of tuberculosis, 778 (90%) claimed they had attended a medical facility for their respiratory symptoms during the previous year, the most recent visit being within the previous month in 24%. All except 1% of the total had attended on more than one occasion, the average number of attendances being 5·3. 83% said they had attended the peripheral health units and 37% had attended the Central District Hospital, yet 65% of the suspects had had neither a chest radiograph nor their sputum examined bacteriologically. Of the 114 cases of tuberculosis registered in the District Tuberculosis Register during the previous 10 years, nine were currently culture-positive, seven being smear-positive. The examination of a second sputum specimen from 105 yielded one more culture-positive case. Of 577 household contacts of the registered cases, seven were culture-positive, three being smear-positive. The examination of a second sputum specimen from 568 yielded two more culture-positive cases. During a full year, only 45 suspects were registered among out-patients attending seven health units serving the area (population 27,500), of whom four were smear-positive. This indicates a failure of the staff to take appropriate actions.

A third study of case-finding methods for pulmonary tuberculosis in kenya, including the use of community leaders

Five methods of identifying tuberculosis suspects were investigated in the Machakos District of Kenya by: (1) 3-monthly interrogation of the Community Elders, (2) interrogation of household heads, (3) identifying suspects amongst outpatients attending local health units, (4) examination of patients registered during the previous 10 years in the District Tuberculosis Register and also (5) their close contacts. Sputum was bacteriologically examined by smear and culture from suspects found by all the methods. The initial interrogation of the Elders yielded 216 suspects, of whom 9 were culture-positive, including 6 smear-positive. Reinterrogating the Elders 4 times at 3-monthly intervals produced a further 114 suspects including 4 culture-positive cases (3 being smear-positive). The examination of a second sputum specimen from suspects after a 3-month interval yielded 4 further culture-positive cases (all smear-negative) but the examination of a third specimen after a further 3 months yielded no further cases. A single interrogation of 1093 household head suspects yielded 22 culture-positive cases, including 11 smear-positive. The response in 5 health units covering a population of about 24 500 was poor. During a 2-year period only 109 suspects were recorded; 7 were culture-positive, including 3 smear-positive. Of 61 cases of tuberculosis registered during the previous 10 years, 8 were currently culture-positive, 5 being smear-positive. Of 318 household contacts of these cases, 6 were culture-positive cases, 2 being smear-positive. The problems presented by different active case-finding methods are discussed, identifying those that appear promising and those unpromising.