Differential misclassification bias and dietary recall for the distant past using a food frequency questionnaire

A Narrative Review of the Role of Diet and Lifestyle Factors in the Development and Prevention of Endometrial Cancer

Simple Summary

The incidence and prevalence of endometrial cancer is increasing globally. The main factors involved in this increase have been the way women live today and what they eat and drink. In fact, the obesity pandemic that is sweeping across the planet is considered to be the main contributory feature. This review aims to introduce to a new audience, those that are not experts in the field, what is known about the different types of endometrial cancer and the mechanisms for their induction and protection. We also seek to summarise the existing knowledge on dietary and lifestyle factors that prevent endometrial development in susceptible populations and identify the main problem in this arena; the paucity of research studies and clinical trials that investigate the interaction(s) between diet, lifestyle and endometrial cancer risk whilst highlighting those areas of promise that should be further investigated.

Abstract

Endometrial cancer is the most common cancer affecting the reproductive organs of women living in higher-income countries. Apart from hormonal influences and genetic predisposition, obesity and metabolic syndrome are increasingly recognised as major factors in endometrial cancer risk, due to changes in lifestyle and diet, whereby high glycaemic index and lipid deposition are prevalent. This is especially true in countries where micronutrients, such as vitamins and minerals are exchanged for high calorific diets and a sedentary lifestyle. In this review, we will survey the currently known lifestyle factors, dietary requirements and hormonal changes that increase an individual’s risk for endometrial cancer and discuss their relevance for clinical management. We also examine the evidence that everyday factors and clinical interventions have on reducing that risk, such that informed healthy choices can be made. In this narrative review, we thus summarise the dietary and lifestyle factors that promote and prevent the incidence of endometrial cancer.

A case-control study on egg consumption and risk of stroke among Iranian population

BACKGROUND

Most available data that linked intake of egg to risk of stroke came from western countries, with conflicting findings. We aimed to examine the association between egg consumption and risk of stroke among Iranian adults.

METHODS

In a hospital-based case-control study, 195 stroke patients, hospitalized in Alzahra University Hospital, were selected as cases and 195 control subjects, from patients hospitalized in other wards with no history of cerebrovascular diseases or neurologic disorders, were recruited. A validated 168-item food frequency questionnaire (FFQ) was used to assess participants' usual dietary intake, including egg consumption, over the previous year. Other required information was gathered by the use of questionnaires.

RESULTS

Consumption of eggs was associated with lower odds of stroke, such that after adjustment for potential confounders, those in the highest category of egg intake (>2 eggs/week) were 77% lower odds to have stroke, compared with those with the lowest category of egg intake (<1 egg/week) (OR 0.23; 95% CI 0.11-0.45). Further controlling for body mass index strengthened the association (OR 0.20; 95% CI 0.09-0.41).

CONCLUSIONS

We found evidence indicating that high intake of eggs (>2 eggs/week) during the past 1 year was associated with a lower risk of stroke. Further prospective studies are required to confirm these findings.

A new approach to measuring partnership concurrency and its association with HIV risk in couples

Empirical estimates of the association between concurrent partnerships (CP) and HIV risk are affected by non-sampling errors in survey data on CPs, e.g., because respondents misreport the extent of their CPs. We propose a new approach to measuring CPs in couples, which permits assessing how respondent errors affect estimates of the association between CPs and HIV risk. Each couple member is asked (1) to report whether s/he has engaged in CPs and (2) to assess whether his/her partner has engaged in CPs, since their couple started. Cross-tabulating these data yields multiple classifications (with varying combinations of sensitivity/specificity) of the CPs of each couple member. We then measure the association between CPs and HIV outcomes according to each classification. The resulting range of estimates is an indicator of the uncertainty associated with respondent errors. We tested this approach using data on 520 matched couples drawn from the Likoma Network Study. Results suggest that existing tests of the concurrency hypothesis are affected by significant uncertainty.

Assessing lifetime diet: reproducibility of a self-administered, non-quantitative FFQ

OBJECTIVE

To demonstrate test-retest reliability (reproducibility) of a new self-administered lifetime diet questionnaire, with a focus on foods relevant to cognitive health in older age.

DESIGN

The reproducibility of dietary recall over four or five life periods was assessed by administering the questionnaire at two time points to an older cohort. The period between questionnaire administrations was 7 weeks. Polychoric correlations measured the association between recall at time 1 and time 2 and the weighted κ statistic measured the level of recall agreement for food groups across the two administrations of the questionnaire.

SETTING

Adelaide, South Australia.

SUBJECTS

Fifty-two cognitively healthy, older-age, community-dwelling adults completed the Lifetime Diet Questionnaire; mean age 81·8 (SD 4·4) years, range 70-90 years.

RESULTS

The questionnaire showed very good reproducibility in this sample with a mean polychoric correlation coefficient of 0·81 between administration at time 1 and time 2, and an average weighted κ of 0·49 for the level of recall agreement between food groups.

CONCLUSIONS

The demonstrated reliability of this lifetime diet questionnaire makes it a useful tool to assess potential relationships between long-term dietary intake and later-age cognitive outcomes.

Diet-associated risks of disease and self-reported food consumption: how shall we treat partial nonresponse in a food frequency questionnaire?

Using data from a population-based case-control study on thyroid cancer, we studied two approaches of handling missing answers in a food frequency questionnaire when estimating food consumption and nutrient intakes. We analyzed the dietary reports of 165 cases and 248 control subjects. In the first approach, the omitted food items were considered as "null consumption." In the second approach, the missing answers were replaced with the median frequencies for subjects in the corresponding outcome category actually answering that specific food item. The results showed marginal differences between the two methods. In addition, the null consumption assumption was validated by means of complementary telephone interviews with a subsample of subjects who provided incomplete reports. Overall, the originally omitted answers actually corresponded to very rare consumption for 54.2% of cancer patients and for 54.7% of controls. However, this "true" proportion of null consumption varied greatly between different food items (range 0-96%) and between food groups (range 14-82%). To interpret the omitted self-reports of food consumption as indication of "zero consumption" is quite reasonable when the investigation does not focus on dietary items widely consumed in the source population.

An empirical investigation of exposure measurement bias and its components in case-control studies

This study investigated bias due to misclassification of exposure in case control studies. Using a metaanalysis of data from a number of case control studies, in which a possibly misclassified exposure was validated against a more reliable one, estimates of misclassification indices and bias were obtained. The estimates were used to investigate whether misclassification indices, in particular, sensitivity and specificity and so-called quality indices, are typically nondifferential with respect to cases and controls. It is concluded that quality indices do not show any tendency to be either lower or higher in cases than controls. On the other hand, sensitivity tends to be higher in cases than controls and specificity lower. Estimates of misclassification bias may be either positive or negative and are consistent with random variation; there is little to suggest that bias is present in the studies analyzed.

A comparison of prospective and retrospective assessments of diet in a study of colorectal cancer

Dietary factors are widely studied as risk factors for colorectal cancer, with much information from case-control studies. We evaluated the validity of dietary data from a retrospective case-control study of diet and colorectal cancer. As part of the alpha-Tocopherol, beta-Carotene Cancer Prevention Study, diet was assessed at baseline and after diagnosis for colorectal cancer cases and at baseline and regularly during the trial for a random control group. The dietary assessment referred to the previous 12 months (in cases before diagnosis). In the two dietary assessments, the cases reported a greater increase in consumption of fruits and dairy products and a decrease in consumption of potatoes. Accordingly, relative risks for colorectal cancer by baseline dietary data differed markedly from odds ratios from case-control data; e.g., relative risk for a 652-mg increase in calcium intake was 0.79 (95% confidence interval = 0.48-1.30) in case-cohort analysis vs. an odds ratio of 1.57 (95% confidence interval = 1.06-2.33) for case-control analysis. The most likely explanation is the influence of current diet on recall of prediagnosis diet and effects of occult cancer on diet in the year before cancer diagnosis, which have implications for interpretation of case-control studies in evaluating associations between diet and colorectal cancer.

Assessment of ability to recall physical activity of several years ago

In this study we assessed the reliability of recall of physical activity. Study participants were members of the Coronary Artery Risk Development in Young Adult Study (CARDIA) cohort who reported physical activity at each CARDIA examination. In this study, we asked 81 participants to recall activity patterns for the year prior to 2 to 3 years ago so that we could compare recalled activity patterns to those reported 2 to 3 years ago (labeled as "distantly recalled") as well as to activity patterns reported at the other CARDIA examinations. We found that distantly recalled physical activity patterns were highly correlated with those reported at the time of the examination where they were obtained (vigorous activity r = 0.84, moderate activity r = 0.64, and total activity r = 0.81). Distantly recalled activity was less highly associated with activity reported currently (vigorous activity r = 0.57, moderate activity r = 0.45, total activity r = 0.59). The activity recalled the best was jogging or running (r = 0.76) and the activity with the poorest recall was racket sports (r = 0.53). Distantly recalled physical activity also was related to resting pulse rate obtained during the time period of the recalled activity (r = -0.21). These findings suggest that people can recall activity patterns of several years ago with high reliability.

Recall bias in case-control studies: an empirical analysis and theoretical framework

Previous work has suggested that recall bias in case-control studies may be more serious when the overall study quality is lower. This paper summarizes a systematic literature search to examine the question. All relevant studies published between 1966 and 1990 were included if they met the following criteria: (1) they represented original work, (2) they used a human population, (3) they used a case-control design, (4) they had a "validated" gold standard applied equally to cases and controls and (5) they reported at least one of crude agreement rates, chance-corrected agreement rates (kappa), sensitivity or specificity. Sixteen such studies were identified. No relationship was found between the absolute differences in agreement between cases and controls and the overall level of agreement, in contradiction to suggestions in previous literature. Comparisons of the data quality for cases and controls using either the crude agreement level, kappa, sensitivity, or specificity gave linear relationships with correlations of 0.81, 0.78, 0.58 and 0.62 respectively. Kappas were generally lower than the corresponding crude agreement levels and specificities were higher than sensitivities. When used together, these types of comparisons can give valuable information regarding (1) the possible existence of differential recall in a particular study and (2) the quality of that study, A theoretical framework is proposed for use in these areas.

Reconstruction of past calcium intake patterns during adulthood

This study illustrates a cognitive recall method based on time lines and retrieval cues to reconstruct the patterns of use of selected dairy products as important calcium sources. We administered a semiquantitative retrospective instrument that assessed past intakes of milk, milk-based chocolate beverages, and cheese to 35 healthy women aged 50 to 65 years. The recall time line for each subject began at the age of 20 and continued forward to the interview. Thirty-one women reported a change in calcium intake from the baseline level at age 20. Seventeen had changed their intake by more than 50%. Milk was the food item the most subject to change. The magnitude of change along the time line was quite important as intraindividual intakes differed by 100 to 300 mg of calcium per day in 11 women and differed by more than 300 mg of calcium per day in 12 others. After age 50 there was an upward trend in calcium use, which coincides with higher calcium requirements after menopause. Health concerns and food preferences were the prominent motives that triggered changes. The findings suggest that the cognitive recall method could provide necessary information on lifelong food patterns implicated in chronic disease development.

Reliability of dietary information from surrogate respondents

A self-administered food frequency questionnaire was included as part of a case-control study of breast cancer in 1980-82. In 1986-87, a second food frequency questionnaire was sent to surviving cases and husbands of deceased cases; 30 spouses (86% response rate) and 263 surviving cases (88% response rate) returned questionnaires. The dietary questions concerned consumption of specific food items by the case before diagnosis of breast cancer. Missing values were less common in the second questionnaire; there was no significant difference in missing values between surviving cases and spouses of deceased cases. Kappa statistics comparing responses in the first and second questionnaires were significantly lower for spouses of deceased cases than for surviving cases. Reported level of confidence by the husbands regarding knowledge about their wives' eating habits did not influence the kappa statistics or the frequencies of missing values. The lack of good agreement has important implications for the use of proxy interviews from husbands in retrospective dietary studies.

Nutritional risk factors and ovarian cancer

In a hospital-based case-control study, consumption of lactose-containing (dairy) foods and foods containing beta-carotene by 71 women with epithelial cancer of the ovary and 141 matched controls was investigated. No significant differences were found between cases and controls in the frequency of consumption of dairy foods or in the amount of lactose consumed. Consumption of carrots was found to decrease risk. Logistic regression analyses indicated a protective effect of high beta-carotene intake (odds ratio = 0.3, 95% confidence interval = 0.1-0.8), after adjusting for body mass, smoking, and lactose consumption.