Edward J. Stanek

A study to determine the accuracy of cancer mortality data was done using cancer deaths occurring during 1970 and 1971 in eight of the nine areas included in the Third National Cancer Survey (TNCS). Death certificates with an underlying cause of death of cancer were compared to the hospital diagnosis for 48,826 resident cases of single primary cancers. The underlying cause of death as coded on the death certificate was found to be accurate for about 65 per cent of the cancer deaths in this study. Misclassification problems occurred for colorectal cancer, the second leading cause of death from cancer. Colon cancer was overreported and rectal cancer was under-reported on death certificates. Other misclassification problems were found for cancers of the uterus, brain, and buccal cavity including most of its sub-sites. Physicians tended to report a non-specific site of cancer on the death certificate rather than the specific site identified by the hospital diagnosis.

Social desirability (the tendency to respond in such a way as to avoid criticism) and social approval (the tendency to seek praise) are two prominent response set biases evident in answers on structured questionnaires. These biases were tested by comparing nutrient intakes as estimated from a single 24-hour diet recall interview (24 HR) and a 7-day dietary recall (7DDR). Data were collected as part of the Worcester Area Trial for Counseling in Hyperlipidemia, a randomized, physician-delivered nutrition intervention trial for hypercholesterolemic patients conducted in Worcester, Massachusetts, from 1991 to 1995. Of the 1,278 total study subjects, 759 had complete data for analysis. Men overestimated their fat and energy intakes on the 7DDR as compared with the 24HR according to social approval: One unit increase in the social approval score was associated with an overestimate of 21.5 kcal/day in total energy intake and 1.2 g/day in total fat intake. Women, however, underestimated their dietary intakes on the 7DDR relative to the 24HR according to social desirability: One unit increase in the social desirability score was associated with an underestimate of 19.2 kcal/day in energy intake and 0.8 g/day in total fat. The results from the present study indicate that social desirability and social approval biases appear to vary by gender. Such biases may lead to misclassification of dietary exposure estimates resulting in a distortion in the perceived relation between health-related outcomes and exposure to specific foods or nutrients. Because these biases may vary according to the perceived demands of research subjects, it is important that they be assessed in a variety of potential research study populations.

BACKGROUND: Increased concentrations of high-sensitivity C-reactive protein (hs-CRP), a marker of systemic inflammation, are associated with increased risk for coronary heart disease. Because of its relationship to inflammation, hs-CRP has considerable biologic variation. This study was carried out to characterize CRP variation and to compare it to another risk factor, total serum cholesterol. METHODS: One hundred thirteen individuals were scheduled to have five measurements each of hs-CRP and total cholesterol carried out at quarterly intervals over a 1-year period. Variations of hs-CRP and total cholesterol were characterized, and classification accuracy was described and compared for both. RESULTS: The relative variation was comparable for hs-CRP and total cholesterol. When classified by quartile, 63% of first and second hs-CRP measurements were in agreement; for total cholesterol it was 60%. Ninety percent of hs-CRP measurements were within one quartile of each other. This relationship was not altered by the use of log-transformed hs-CRP data. CONCLUSION: hs-CRP has a degree of measurement stability that is similar to that of total cholesterol.

BACKGROUND: A variety of studies have noted seasonal variation in blood lipid levels. Although the mechanism for this phenomenon is not clear, such variation could result in larger numbers of people being diagnosed as having hypercholesterolemia during the winter. METHODS: We conducted a longitudinal study of seasonal variation in lipid levels in 517 healthy volunteers from a health maintenance organization serving central Massachusetts. Data collected during a 12-month period for each individual included baseline demographics and quarterly anthropometric, blood lipid, dietary, physical activity, light exposure, and behavioral information. Data were analyzed using sinusoidal regression modeling techniques. RESULTS: The average total cholesterol level was 222 mg/dL (5.75 mmol/L) in men and 213 mg/dL (5.52 mmol/L) in women. Amplitude of seasonal variation was 3.9 mg/dL (0.10 mmol/L) in men, with a peak in December, and 5.4 mg/dL (0.14 mmol/L) in women, with a peak in January. Seasonal amplitude was greater in hypercholesterolemic participants. Seasonal changes in plasma volume explained a substantial proportion of the observed variation. Overall, 22% more participants had total cholesterol levels of 240 mg/dL or greater (> or =6.22 mmol/L) in the winter than in the summer. CONCLUSIONS: This study confirms seasonal variation in blood lipid levels and suggests greater amplitude in seasonal variability in women and hypercholesterolemic individuals, with changes in plasma volume accounting for much of the variation. A relative plasma hypervolemia during the summer seems to be linked to increases in temperature and/or physical activity. These findings have implications for lipid screening guidelines. Further research is needed to better understand the effects of a relative winter hemoconcentration.