Daniel Seigel

Risk factors for hemiretinal vein occlusion : Comparison with risk factors for central and branch retinal vein occlusion the eye disease case-control study

OBJECTIVE Possible risk factors for hemiretinal vein occlusion were identified and compared with risk factor profiles for central and branch retinal vein occlusion. DESIGN The design was a multicenter case-control study. METHODS The authors identified 79 patients with hemiretinal vein occlusion (HRVO), 258 patients with central retinal vein occlusion (CRVO), 270 patients with branch retinal vein occlusion (BRVO), and 1142 control subjects at 5 clinical centers. Risk factor data were obtained through interviews, clinical examinations, and laboratory analyses of blood specimens. RESULTS Systemic hypertension and history of diabetes mellitus were associated with increased risk of HRVO. Risk of CRVO increased with history of diabetes, systemic hypertension, and higher erythrocyte sedimentation rate (females only); risk of CRVO decreased with increasing amounts of physical activity and increasing amounts of alcohol consumption. Systemic hypertension, higher body mass index, and higher alpha2-globulin levels were associated with increased risk of BRVO, whereas higher high-density lipoprotein levels and increasing levels of alcohol consumption were associated with decreased risk of BRVO. Glaucoma history was associated with all three types of retinal vein occlusion. CONCLUSION Patients presenting with retinal vein occlusion should be evaluated for cardiovascular disease, diabetes, and glaucoma.

Senile lens and senile macular changes in a population-based sample.

Eye examinations performed on the survivors of the Framingham Heart Study Cohort showed a prevalence of senile lens changes ranging from 42% at ages 52 to 64 years to 91% at ages 75 to 85 years. The prevalence of senile macular changes increased from 35% at 52 to 64 years to 50% at 75 to 85 years. Persons affected with either condition usually had bilateral involvement. No association between the two conditions was shown.

Survival Rates After Enucleation of Eyes with Malignant Melanoma

We investigated the rates of mortality for several types of malignant melanomas for evidence that surgery accelerates metastasis. Additionally, we reanalyzed uveal melanoma survival rates from the Armed Forces Institute of Pathology. Our computations showed higher death rates in years two to five after diagnosis than in years one or six to ten. The same pattern of a peak mortality in the early years after diagnosis and lower rates six to ten years thereafter was seen in all tumor types studied. Our analysis of survival rates produced no evidence to alter the existing pattern of treatment for malignant melanoma of the uvea.

Several Approaches for Measuring Average Rates of Change for a Second Degree Polynomial

Sometimes it is desirable to obtain single summary estimates of rates of change for curved lines. For example, an investor may be interested in what is likely to be his yearly capital gains and may be willing to ignore fluctuations over shorter time intervals, even if they are real. A biologist may w-ish to examine average growth per unit time in an organism whose growth is exactly described by a second degree curve. Further, comparisons of rates of change for tw o populations may be required where one is linear and the other curvilinear. In this paper we shall discuss some statistics that might be employed to characterize rates of change for the second degree curve and examine the ways in which they differ.

Serum zinc and serum lipid profiles in 778 adults

There has been increasing use of high-dosage zinc supplementation in the population, in particular as a potential treatment for age-related macular degeneration. We examined the relationship between fasting serum zinc and serum lipid levels in 778 adults, aged 22 to 80 years, who were control subjects in a multicenter, clinic-based case-control study. The samples were taken during 1987 to 1990, a time when vitamin/mineral supplementation was becoming increasingly common. We found that higher serum zinc levels, most notably those above the highest quintile, were associated with higher levels of total serum cholesterol, low-density-lipoprotein cholesterol, and triglycerides. No significant trend was noted for high-density-lipoprotein cholesterol. Previous studies demonstrated that high-dosage zinc supplements raise serum zinc levels. The possibility that use of such supplements can adversely affect serum lipid profiles suggests that chronic ingestion of such supplements should not be done without adequate medical supervision.

Should Data Be Collected on a Dependent Variable Late in a Clinical Trial if Not Measured at Baseline

There is an experience I have now had several times in my work in clinical trials, suggesting widespread disagreement and confusion with respect to some fundamental concepts. I have written this short communication to focus attention on the subject so that we can, through discussion, understand one another better. The problem typically develops when all or most subjects in a clinical trial, after having been recruited and assigned randomized treatments, are well along in follow-up. The investigators think of a new dependent variable that permits further evaluation of the treatment. There is an opportunity to measure this variable at each patient’s final visit. Is it reasonable to consider doing so, even though the variable was not measured at baseline? I would like to illustrate the issues by way of a dialogue that might occur:

Consistency of incidence, survival, and prevalence data on myocardial infarction from various studies

Abstract Comparisons in levels of heart disease in different studies have been restricted to the same type of measure, such as incidence in each of two population groups. In this paper comparisons were made among different types of measures to see whether they were consistent with the estimates of the prevalence of myocardial infarction yielded by the Health Examination Survey Program. The analysis suggests that estimates of incidence among females from the Framingham Heart Study are lower than one would expect. The technique used was essentially that of a life table and may be of value where comparisons of this type are required.

LIFE TABLE RATES AND PERSON MONTH RATIOS AS SUMMARY STATISTICS FOR CONTRACEPTIVE TRIALS

SUMMARY Person month statistics consist of ratios of events divided by months of exposure to the risk of such events. They are required as part of the procedure for computing life table rates. If person month statistics are presented for relatively short intervals of contraceptive use, such as the first three months, the second three months, etc. the pitfalls in their use are averted and they constitute a simple and useful statistical methodology. For those who are interested in converting them to life table rates, they can easily do so from published person year data.

Life table rates and person month ratios as summary statistics for contraceptive trials

Abstract Person month statistics consist of ratios of events divided by months of exposure to the risk of such events. They are required as part of the procedure for computing life table rates. If person month statistics are presented for relatively short intervals of contraceptive use, such as the first three months, the second three months, etc. the pitfalls in their use are averted and they constitute a simple and useful statistical methodology. For those who are interested in converting them to life table rates, they can easily do so from published person year data.

Oral Contraceptives and Excess Mortality From Venous and Pulmonary Thromboembolism in the United States

Analysis of trends in mortality from thromboembolic disorders in women in the reproductive ages was motivated by two types of information. The first is that the proportion of women who are using oral contraceptives is large, estimated in a national survey in 1965 to be 15% of married women under age 45 (1). The second is that the risk of death from pulmonary embolism or cerebral thrombosis has been reported to be increased by a factor of 8 in these women (2). The combination of a large proportion of oral contraceptive users with such an increased risk should produce a doubling in the overall national mortality from these causes for women in the childbearing ages.