Search PubMed⌕ Search

Biomedical subjects

F Ederer

Publications and source records attributed to F Ederer.

At least 19 recordsLinked to original sources
PubMed1989

Sensitivity, specificity, and positive predictivity of the Hemoccult test in screening for colorectal cancers. The University of Minnesota's Colon Cancer Control Study.

Data are presented on the sensitivity, specificity, and positive predictivity of the Hemoccult test based on the experience of the Minnesota Colon Cancer Control Study, a randomized clinical trial to determine whether the use of the Hemoccult test can reduce mortality from colorectal cancer. Rehydrating the slides with a drop of water before processing resulted in an increase in positivity (2.4% to 9.8%), and sensitivity (80.8% to 92.2%) but a decrease in specificity (97.7% to 90.4%) and positive predictivity (5.6% to 2.2%). The effects of age and sex were also evaluated. The test was less specific for men than women (p = 0.03). Specificity was highest for those less than 60 yr of age and decreased with increasing age (p = 0.05). The positive predictivity increased with age from 1.6% for those under 60 yr to 3.6% for those over 70 yr (p = 0.0004).

Age Factors↗
PubMed1986

Epidemiologic associations with nuclear, cortical, and posterior subcapsular cataracts.

Data from the 1971-1972 National Health and Nutrition Examination Survey were used to examine the associations between specific cataract types and age, race, sex, number of years spent in school, diabetes, systolic blood pressure, urban versus rural residence, and average daily ultraviolet spectrum B (UV-B) radiation counts at the site of examination. Separate comparisons were made of persons with no lens changes (n = 1,299) and persons with cortical (n = 55), nuclear (n = 104), and posterior subcapsular cataracts (n = 18). Persons with more than one type of cataract were excluded from the analysis. Cortical cataracts were associated with age (relative risk (RR) = 11.4 for age 70 years vs. age 50 years), race (RR = 3.5 for blacks vs. whites), sex (RR = 3.0 for women vs. men), educational achievement (RR = 1.8 for less than nine years of schooling vs. college), and UV-B count (RR = 3.6 for 6.0 X 10(3) counts vs. (2.6 X 10(3) counts). Nuclear cataracts were associated with age (RR = 38.6 for age 70 years vs. age 50 years), race (RR = 1.8 for black vs. white), and residence (RR = 1.6 for rural vs. urban). Posterior subcapsular cataracts were associated with diabetes (RR = 6.6 for diabetes present vs. diabetes absent) and systolic blood pressure (RR = 2.2 for 160 mmHg vs. 120 mmHg). Cortical cataracts were more common in women and more often found in locations with increased UV-B radiation counts than either nuclear or posterior subcapsular cataracts. In diabetics, the risk of posterior subcapsular cataracts was greater than the risk of nuclear cataracts (p less than 0.05) and also appeared to be greater than the risk of cortical cataracts (p = 0.06).

Age Factors↗
PubMed1986

Lessons from the Visual Acuity Impairment Survey pilot study.

The Visual Acuity Impairment Survey (VAIS) pilot study was carried out in three large metropolitan areas of the United States to determine whether it would be feasible to conduct a large two-stage survey of the prevalence of visual acuity impairment and its causes. The study was conducted in conjunction with the Health Interview Survey (HIS), performed by the National Center for Health Statistics and the Census Bureau. In the first stage, a simple vision screening test was administered to 1,868 adults in their homes by specially trained Census Bureau interviewers. All those who failed the test, and a sample of those who passed it, were invited to a local clinic for a check on the accuracy of the screen and a detailed eye examination to establish the cause of the impairment. About 89 per cent of the HIS interviewees took the vision screening test in the home and agreed to have the results released, making it possible for the clinic to invite them for an examination. The principal obstacle to the success of the feasibility study was a low rate (less than 50 per cent) of participation in the clinic examination by the target population. Such low participation would leave the survey open to a serious question about its representativeness. The methods and findings of the pilot study are presented because the lessons may be of value to those attempting similar studies in the future. Suggestions are made for methodological modifications that may enhance the chances for success.

Adult↗
PubMed1985

Factors influencing the development of visual loss in advanced diabetic retinopathy. Diabetic Retinopathy Study (DRS) Report No. 10.

Natural history data from the Diabetic Retinopathy Study were examined by multivariate methods to determine which baseline characteristics could predict the occurrence of severe visual loss (SVL) in eyes originally assigned to no treatment. The presence and extent of new blood vessels on the optic disc (NVD) had the strongest association with SVL. Several other ocular characteristics also were strongly associated with visual outcome. In the absence of NVD at baseline, the degree of intraretinal hemorrhages and microaneurysms (HMA) had the strongest association with development of SVL. Macular edema was a factor in determining visual loss to 20/200 but not SVL (less than 5/200). Among systemic characteristics, urinary protein was the best predictor of visual outcome, but none were as good as the major ocular variables.

Blindness↗
PubMed1984

Assessing possible late treatment effects in stopping a clinical trial early: a case study. Diabetic Retinopathy Study report No. 9.

Suppose a fixed-sample trial in a disease with a long response time shows a statistically significant benefit of the experimental treatment before patients have completed the planned follow-up period. The question may then arise--and did arise in the Diabetic Retinopathy Study (DRS)--whether the observed early benefit of treatment may be offset at some time in the future by the subsequent development of harmful treatment effects. If this question raises serious concerns, then the investigators are faced with a dilemma. If the trial is stopped because of the observed early treatment benefit and the treatment is administered to the untreated control group as well as to patients outside the study, and if the treatment is later found to have deleterious effects, then it may ultimately do more harm than good to patients. Moreover, the fact that the treatment is harmful may never become known. If, on the other hand, the trial is not stopped and the treatment proves to have no deleterious effects, then the control group and patients outside the study would be harmed because the treatment was withheld. We show how, in the DRS, this very problem was formulated and resolved. First a severe, delayed harmful treatment effect was postulated. Projections based on this postulation showed that the early gains were so great that they were unlikely to be offset--ever. Based in part on these projections, the following decisions were made: (a) the study protocol would be changed so as to allow treatment of the untreated control group, and (b) patients would continue to be followed in order to make possible the detection of late, harmful treatment effects, should they develop.

Clinical Trials as Topic↗
PubMed1983

Incidence estimates for lens changes, macular changes, open-angle glaucoma and diabetic retinopathy.

Incidence data are lacking for common eye conditions. The authors previously developed a method for estimating incidence from age-specific prevalences for diseases that are irreversible and not associated with differential mortality (Am J Epidemiol 1981;113:606-13). This method is now used to estimate age-specific incidences for senile lens changes, senile cataracts, macular changes, senile macular degeneration, open-angle glaucoma, and diabetic retinopathy. Using age-specific prevalence data from the Framingham Eye Study, five-year incidence rates were estimated for ages 55, 60, 65, 70, and 75. For each condition, estimated incidence increased with age: incidence estimates ranged from 10% to 37% for senile lens changes, from 1% to 15% for senile cataracts, from 3% to 6% for macular changes, from 0.5% to 7% for senile macular degeneration, from 0.2% to 1% for open-angle glaucoma, and, among diabetics, from 3% to 5% for diabetic retinopathy. Standard errors were small for senile lens changes and senile cataracts, but large (of about the same magnitude as the incidence estimates) for macular changes, senile macular degeneration, open-angle glaucoma, and diabetic retinopathy. These estimates may be useful as approximations of the true incidence rates in planning epidemiologic research.

Aged↗
PubMed1983

Epidemiologic associations with cataract in the 1971-1972 National Health and Nutrition Examination Survey.

Data from the 1971-1972 National Health and Nutrition Examination Survey were used to examine the associations between cataract and age, race, sex, education, diabetes, systolic blood pressure, urban vs. rural residence, and average daily ultraviolet spectrum B (UV-B) radiation counts at the site of examination. The multivariate logistic risk function was applied to data on 2225 persons, aged 45-74, who had resided for at least half their lifetime in the state where their examination was conducted. Cataracts (cortical, nuclear or posterior subcapsular opacities consistent with best corrected visual acuity of 6/9 (20/30) or worse or aphakic status) were present in 413 persons. The multivariate analysis showed that they were more common among blacks, diabetics, and rural dwellers, and were positively associated with increasing age, increasing UV-B radiation counts at the site of the examination, and decreasing number of years spent in school. The association with cataracts was also present when latitude or sunlight hours was substituted for UV-B radiation counts.

Aged↗
PubMed1983

Methodological problems in eye disease epidemiology.

The recent burst of activity in eye disease epidemiology, occasioned by increases in the number of ophthalmologists with training in epidemiology and of epidemiologists interested in eye diseases, makes this an appropriate time for taking stock of methodological problems in this field. In this review, based largely on the author's personal encounter with five large epidemiologic studies (2, 7, 19, 30, 39) of the four major chronic eye diseases (senile cataract, senile macular degeneration, diabetic retinopathy, and glaucoma), the following methodological areas are discussed: quality assurance; disease definitions and classifications; reproducibility of observations; visual acuity and visual field tests; needed technologic advances; study design of case-control studies and clinical trials; and data analysis (shall we count subjects or eyes?). The chief weakness of blindness registers has been inadequate evaluation of the extent of underregistration and of the variability of underregistration according to socioeconomic and racial subgroups. The Health and Nutrition Examination Survey (HANES), conducted by the United States Public Health Service, is a potentially valuable source of descriptive and analytic epidemiologic information on eye diseases. It is an examination of a large probability sample of the US population and includes various histories, clinical and laboratory examinations, and a nutrition interview. In the early 1970s, HANES included eye examinations, but these were curtailed because of inability to get ophthalmologists as examiners. In future HANES studies, efforts should be made to minimize the involvement of ophthalmologists in the eye examinations and to increase the use of nonophthalmologists (e.g., optometrists, technicians) and instruments (e.g., cameras, densitometers, automated perimeters). The validity and reliability of any new procedures will need to be determined. Studies may need to be limited to certain major eye diseases and conditions. Population glaucoma surveys have tended to omit partially or entirely the time-consuming visual field test. Yet, without this test, the diagnostic examination for glaucoma is incomplete. The automated perimeter, with which visual fields can be more quickly measured, promises to be an important screening tool for glaucoma prevalence and case-finding surveys. It should be field-tested for epidemiologic use. The absence of standardized disease definitions, without which comparisons between studies are uncertain, has been a handicap to epidemiologic research in eye disease. A first constructive step toward the development of disease definitions would be the development of disease classifications.(ABSTRACT TRUNCATED AT 400 WORDS)

Blindness↗
PubMed1979

Prognosis for life in patients with diabetes: relation to severity of retinopathy.

In a group of 709 individuals with diabetes diagnosed prior to age 50 and followed for five to thirteen years a strong inverse relationship was demonstrated between the severity of the retinopathy at the initial visit and survival. Survival in patients with no retinopathy or with microaneurysms only was little different from that of the general population (five-year rate .99, SE .01). The five-year survival rate for patients with more severe nonproliferative retinopathy, characterized by the presence of hemorrhages and/or exudates, but without new vessels or vitreous hemorrhage (B2), was .81 (SE .04), and that for patients with proliferative retinopathy (PDR) was .56 (SE .03). After adjustment for age at diagnosis of diabetes, duration of diabetes and sex, the differences in survival between these three groups were highly statistically significant. Impairment of visual acuity was also shown to be inversely related to survival. The five-year survival rate for patients with visual acuity of 20/200 or worse in each eye was .42 (SE .05). In patients with B2 retinopathy there was a weak but statistically significant trend towards decreasing survival with increasing duration of diabetes. In patients with PDR survival decreased with increasing duration up to 20 years, but then improved for patients with 20 years or more of diabetes.

Adolescent↗