Empirical study of parental recall bias

Recall bias is a major concern in case-control studies in which questionnaire data are used to assess past exposure. The authors conducted a validation substudy within the framework of a parent case-control study on risk factors for acute lymphoblastic leukemia in children aged < or =9 years diagnosed in 1980-1993 in Quebec, Canada. Parental recall bias for two variables was assessed: reported distance from home to power lines compared with measured distance and reported prenatal radiographic examinations compared with hospital medical record data. For reported distance, sensitivity was 62% for a subgroup of cases living in an area in which an excess of childhood acute lymphoblastic leukemia was perceived and was attributed to power lines. However, for other cases, sensitivity (35%) was similar to that measured for hospital controls (36%) and was relatively close to that for population controls (22%). Specificity was high for all groups except cases from the area with a perceived excess. Sensitivity for reported prenatal radiographic examinations was similar for cases (64%) and population controls (71%) but was lower for hospital controls (50%). Results confirm that under special circumstances, such as those resulting from enhanced public concern, parental recall can be differential but otherwise is most often nondifferential, with low sensitivity. Choosing the best type of controls to ensure comparable recall accuracy remains difficult.     

Potential for bias in case-control studies of oral contraceptives and breast cancer

The discrepancies between the findings of the 6 large case-control studies to study the association between oral contraceptive (OC) use and breast cancer diagnosed in the 1980s may be due to chance or bias. The likelihood that chance played a role is suggested by the large numbers of subgroups examined in each study, the inconsistencies in the findings of different studies, and the wide confidence intervals around most of the relative risks. The most serious potential problem in case-control studies is that the procedures used to select cases and controls may produce groups that are not truly comparable. Recall bias is likely to contaminate information about the duration and type of part OC use. In addition, the more frequent examination of the breasts of women using OCs can produce surveillance bias. 6 procedures are recommended to minimize bias in future case-control studies of OC use and breast cancer: 1) whenever possible, cases and controls should be selected from an entire community; 2) if hospital controls need to be used, there should be explicit criteria for selecting them and the proportions of OC users in each diagnostic group should be presented; 3) women interviewed should not be aware of the study's hypotheses; 4) interviewers should be kept blind as to whether a subject is a case or control; 5) the possibility of recall bias should be investigated by comparing contraceptive histories from a sample of cases and controls with an independent source of information (preferably recorded before cancers were diagnosed); and 7) the interview should include questions about the frequency of breast examinations, so that any effects of more frequent surveillance of OC users can be controlled for.     

Recall Bias in Melanoma Risk Factors and Measurement Error Effects: A Nested Case-Control Study Within the Norwegian Women and Cancer Study

Case-control studies of melanoma have the potential for recallbias after much public information about the relation with ultravioletradiation. Recall bias has been investigated in few studiesand only for some risk factors. A nested case-control studyof recall bias was conducted in 2004 within the Norwegian Womenand Cancer Study: 208 melanoma cases and 2,080 matched controlswere invited. Data were analyzed for 162 cases (response, 78%)and 1,242 controls (response, 77%). Questionnaire responsesto several host factors and ultraviolet exposures collectedat enrollment in 1991–1997 and in 2004 were compared stratifiedon case-control status. Shifts in responses were observed amongboth cases and controls, but a shift in cases was observed onlyfor skin color after chronic sun exposure, and a larger shiftin cases was observed for nevi. Weighted kappa was lower forcases than for controls for most age intervals of sunburn, sunbathingvacations, and solarium use. Differences in odds ratio estimatesof melanoma based on prospective and retrospective measurementsindicate measurement error that is difficult to characterize.The authors conclude that indications of recall bias were foundin this sample of Norwegian women, but that the results wereinconsistent for the different exposures. bias (epidemiology); case-control studies; cohort studies; epidemiologic measurements; melanoma; questionnaires; reproducibility of results; risk factors     

Diet and the risk of breast cancer in a case-control study: does the threat of disease have an influence on recall bias?

It has been suggested that recall bias may explain the discrepant results between case-control and cohort studies on diet and the risk of breast cancer. Two control groups were used for this case-control study of 25 to 75-year-old breast cancer cases (n = 310). The first group consisted of population controls drawn from the Finnish National Population Register (n = 454). The second group consisted of women who were referred to the same examinations as were the cases because of clinical suspicion of breast disease but who were later diagnosed as healthy (referral controls; n = 506). Because the diagnosis was unknown at the time of interview, it was possible to assess by comparing the two control groups whether the self-reporting of diet changed under the threat of disease. Dietary habits were examined using a validated, self-administered food-frequency questionnaire. Premenopausal women misreported their consumption of liquid milk products, tea, and sugar. Reporting bias was also associated with the intake of fat and vitamins. Postmenopausal women misreported consumption of milk products. When recall bias was taken into consideration, milk was associated with increased risk of premenopausal breast cancer, whereas high consumption of poultry or high intake of monounsaturated fatty acids, n-3 fatty acids, n-6 fatty acids, and vitamin E were related to lower risk. The study suggested that oil, milk, cheese, coffee and beta-carotene may act as protective factors in postmenopausal women, whereas butter and cream may be risk factors for breast cancer. In summary, it is possible that some food items may be overreported or underreported under the threat of disease in health-conscious population. However, most of the results in this study were not modified by recall bias.     

Evidence of recall bias in volunteered vs. prompted responses about occupational exposures

BACKGROUND: Recall bias remains a concern in case-control studies, although few investigations have found evidence of differential recall. This study examined whether differences in occupational exposure reporting occur in volunteered vs. prompted questionnaire responses. METHODS: In a large, population-based, case-control study of a childhood cancer, neuroblastoma, we calculated odds ratios for broad occupational exposure groups on the assumption that in the absence of recall bias, risk estimates for such broad groupings should be close to the null value. RESULTS: Prompted exposures and work activities showed little evidence of differential recall by parents of cases and controls (all OR < 1.2), but case parents were more likely to volunteer information about other exposures or activities (ORs: 1.35-1.71). Case mothers were also more likely than control mothers to report activities involving indirect exposure (OR = 1.41). CONCLUSIONS: These findings suggest that prompted exposure questions are less likely to be subject to recall bias than open-ended questions.     

The effects of recall errors and of selection bias in epidemiologic studies of mobile phone use and cancer risk

This paper examines the effects of systematic and random errors in recall and of selection bias in case-control studies of mobile phone use and cancer. These sensitivity analyses are based on Monte-Carlo computer simulations and were carried out within the INTERPHONE Study, an international collaborative case-control study in 13 countries. Recall error scenarios simulated plausible values of random and systematic, non-differential and differential recall errors in amount of mobile phone use reported by study subjects. Plausible values for the recall error were obtained from validation studies. Selection bias scenarios assumed varying selection probabilities for cases and controls, mobile phone users, and non-users. Where possible these selection probabilities were based on existing information from non-respondents in INTERPHONE. Simulations used exposure distributions based on existing INTERPHONE data and assumed varying levels of the true risk of brain cancer related to mobile phone use. Results suggest that random recall errors of plausible levels can lead to a large underestimation in the risk of brain cancer associated with mobile phone use. Random errors were found to have larger impact than plausible systematic errors. Differential errors in recall had very little additional impact in the presence of large random errors. Selection bias resulting from underselection of unexposed controls led to J-shaped exposure-response patterns, with risk apparently decreasing at low to moderate exposure levels. The present results, in conjunction with those of the validation studies conducted within the INTERPHONE study, will play an important role in the interpretation of existing and future case-control studies of mobile phone use and cancer risk, including the INTERPHONE study.     

Recall bias in self-reported melanoma risk factors

The evidence implicating sun exposure in the etiology of melanoma derives largely from case-control studies in which the retrospective assessment of sun exposure suggests potential for significant recall bias. Previous attempts at characterizing and quantifying that bias have had significant methodological limitations. In the International Twin Study, a case-control study of melanoma risk factors in twins conducted from 1980 to 1991, the authors asked melanoma cases and their co-twins to quantify their own exposures and asked which twin had the greater exposure. Recall bias was investigated by assuming that, if bias had occurred, the odds ratio based on the case's response would differ significantly from the odds ratio based on the co-twin's response. Case-derived odds ratios were higher than the odds ratios for the controls for sunbathing in childhood and adulthood and for mole frequency and freckling in childhood, suggesting some recall bias. The odds ratios for ease of burning and tanning appeared unbiased. The belief that sunlight was a cause of melanoma appeared related to an increased odds ratio for sunbathing as a child. There is a continuing need to carefully assess recall bias in the study of melanoma risk factors.     

Reporting and selection bias in case-control studies of congenital malformations.

Retrospective studies of congenital malformations frequently rely on exposures reported by study subjects. Differential error in exposure reporting by cases and controls, which has alternatively been referred to as "recall bias" and "reporting bias," may result in a biased effect measure. Some authors have attempted to avoid reporting bias by comparing exposures between two malformed groups, rather than between cases and nonmalformed controls. This approach, however, may introduce its own bias, which we call selection bias. Both reporting bias and selection bias are shown to be algebraically equivalent to bias arising from exposure misclassification. The magnitudes of these biases are compared for a range of plausible parametric values. The case-control design is sensitive to both differential reporting and selection bias, and the choice of study design involves balancing these two sources of bias.     

Recall strategies used by respondents to complete a food frequency questionnaire: an exploratory study

The purpose of this study was to identify strategies used to recall dietary intake on a food frequency questionnaire by adults in a multiethnic sample. One-on-one interviews were conducted to identify strategies used to recall intake on the Fred Hutchinson Food Frequency Questionnaire. Twenty-eight men and 26 women in San Diego, CA (average age, 41 years), were recruited from the general community with approximately equal numbers of non-Hispanic white, African-American, and English- and Spanish-speaking Hispanic participants. Recall of food intake was most commonly guided by routines. Recall strategies differed primarily by food type and not by ethnic or sex groups. Each of nine food categories on the questionnaire was associated with a distinct pattern of recall strategies. The recall strategies identified in this study may serve as cues to be included on food frequency questionnaires to aid recall and thus improve accuracy of self-reported dietary intake.     

Effect of questionnaire design on recall of drug exposure in pregnancy

Case-control studies of antenatal drug exposure and birth defects often rely on maternal recall of drug use in pregnancy. Differential recall among mothers of cases and controls can lead to information bias ("maternal recall bias"), and the opportunity for such bias increases as ascertainment of drug exposure diminishes. The effect of questionnaire design on the ascertainment of drug use in pregnancy was examined in two studies. In a pilot interview study of 532 women in obstetric/gynecologic practices, information on drug use in the past year was obtained by means of three questions asked in sequence: The first question was open-ended, the second asked about drug use for selected indications, and the third asked about use of specifically named drugs. Among obstetric patients who reported use of any of five drugs, less than 50% did so in response to the open-ended question, and approximately 20-40% reported use only when the specific drug name was asked. In a case-control Birth Defects Study of 5,435 mothers of malformed children, information on drug use in pregnancy was obtained by asking questions in sequence about indications and specifically named drugs. Among the women who reported use of any of 11 drugs, 6-40% did so only when asked about the specific drug by name. These findings suggest that completeness of ascertainment of antenatal drug exposure varies according to how the mother is questioned and is directly related to the specificity of the questions asked.     

Memory of food intake in the distant past

Long term recalls of dietary intake are frequently used in case-control studies, but their validity and reliability have not been established. In this study, 91 middle-aged adults (median age, 50 years) who were participants in the Longitudinal Study of Child Health and Development at the Harvard School of Public Health in Boston, Massachusetts, starting in the early 1930s, were asked in 1984-1985 to report present food intake and to recall food intakes at ages 5-7 years. 18 years, and 30 years using food frequency questionnaires. Their recalled intakes were validated by comparison with historical records of intake collected during the earlier time periods. Recall of food intake in the distant past was a better predictor of historical intake than was current diet. However, correlations between recalled and historical consumption for individual foods and food groups were generally low, rarely exceeding 0.3. Current intakes exerted a powerful influence on accuracy of recall. The consideration of participant characteristics did not prove to be consistently useful in explaining variations in food item and food group-related recall. The authors conclude that recall of food intake in the distant past may be a sufficiently valid estimate of past intake to justify its collection.     

SNP mistyping in genotyping arrays--an important cause of spurious association in case-control studies

Using genome-wide association studies to identify genetic variants contributing to disease has been highly successful with many novel genetic predispositions identified and biological pathways revealed. Several pitfalls for spurious association or non-replication have been highlighted: from population structure, automated genotype scoring for cases and controls, to age-varying association. We describe an important yet unreported source of bias in case-control studies due to variations in chip technology between different commercial array releases. As cases are commonly genotyped with newer arrays and freely available control resources are frequently used for comparison, there exists an important potential for false associations which are robust to standard quality control and replication design.     

An investigation of recall bias in the reporting of past food intake among breast cancer cases and controls.

A nested case-control study was conducted within the Canadian National Breast Screening Study to examine whether there was evidence for biased reporting of past food intake. A total of 325 case patients with breast cancer and 628 matched control subjects completed a self-administered food frequency questionnaire in 1988, recalling their diets originally reported on enrollment into the National Breast Screening Study between 1982 and 1985. Recall of food items was very similar for case patients and control subjects. The magnitude of the odds ratios for the association between these food groups and breast cancer from the prospectively and retrospectively collected data was not systematically different. There was little evidence for recall bias in the reporting of past food intake from these data.     

Cancer case-control studies with other cancers as controls

Theoretical considerations concerning the use of other cancer patients as controls in cancer case-control studies are reviewed. Selection bias may be a problem in that some other cancers may be caused by the exposure under study biasing the odds ratio towards unity. Such bias is noted to be greatest with low prevalence exposures associated with high attributable risks for other cancers. However, it may be possible to identify selection bias with other cancer controls using census or other general population data. In addition, using other cancers as controls has important advantages with regard to recall and interviewer bias, which may be of unknown magnitude and direction when using general population controls. A further disadvantage of general population controls is that separate selection of decreased controls should usually be made for deceased cases, whereas a mixture of live and deceased controls can be expected when selecting other cancer patients as controls. Since there are also logistical and cost advantages in using other cancer patients as controls, this study design is likely to be used increasingly in the future, particularly in cancer registry settings.     

Recall bias in the assessment of exposure to mobile phones

Most studies of mobile phone use are case-control studies that rely on participants' reports of past phone use for their exposure assessment. Differential errors in recalled phone use are a major concern in such studies. INTERPHONE, a multinational case-control study of brain tumour risk and mobile phone use, included validation studies to quantify such errors and evaluate the potential for recall bias. Mobile phone records of 212 cases and 296 controls were collected from network operators in three INTERPHONE countries over an average of 2 years, and compared with mobile phone use reported at interview. The ratio of reported to recorded phone use was analysed as measure of agreement. Mean ratios were virtually the same for cases and controls: both underestimated number of calls by a factor of 0.81 and overestimated call duration by a factor of 1.4. For cases, but not controls, ratios increased with increasing time before the interview; however, these trends were based on few subjects with long-term data. Ratios increased by level of use. Random recall errors were large. In conclusion, there was little evidence for differential recall errors overall or in recent time periods. However, apparent overestimation by cases in more distant time periods could cause positive bias in estimates of disease risk associated with mobile phone use.     

Influence of question structure on the recall of self-reported drug use

Epidemiological studies often rely on self-reported information as a source of drug exposure. Several studies have evaluated the accuracy of self-reported information on drug use. The influence of question structure on the accuracy of recall, however, has not been studied extensively in these studies. In this study we examined the recall accuracy of questionnaire information on drug use in a ongoing public health survey with special attention to the influence of question structure on sensitivity of recall. A sample of 372 hypertensive subjects for whom questionnaire information and pharmacy records were available was examined. Self-reported information on drug use was obtained through questions about medications used for a specific condition and one final open-ended question. This information was compared with the pharmacy medication history. About 71% of all drugs that were currently in use according to the pharmacy records were recalled through the self-administered questionnaire, and 94% of all drugs mentioned in the questionnaire could be traced in the pharmacy records. Recall sensitivity was higher for questions about medications used for a specific indication (88%) than for the open-ended question (41%). The type of drug that was used might have caused part of this difference in recall. We conclude that questionnaire structure might be of influence on the accuracy of recall of self-reported drug use, and more attention should be paid to the structure of questions on drug use.     

Invited Commentary: Recall Bias in Melanoma--Much Ado About Almost Nothing?

Recall bias has been given considerable attention in textbooksand methodological research because of its potential to jeopardizethe validity of epidemiologic results. Case-control studieson self-reported ultraviolet radiation exposure as a risk factorfor melanoma have been described as especially prone to thedeleterious effect of recall bias because of the growing publicawareness about these risks. Using an ideal test-retest designin a large nested case-control study, Parr et al. (Am J Epidemiol.2009;169(3):257–266) examined to what extent recall biasin melanoma risk factors is actually identifiable and whichconsequences its presence has on effect estimates of these riskfactors. They found only minor indications of recall bias, showingan inconsistent overall pattern and a quite negligible effecton risk estimates. Recall bias was not observed in those exposureswhere it was most expected (solarium use and other ultravioletradiation-related exposures). Their findings cannot be usedas an argument that future case-control studies in melanomaepidemiology should be avoided because of the biasing effectof recall bias. bias (epidemiology); dermatology; epidemiologic methods; melanoma; ultraviolet rays     

The effect of recall bias on the association of calorie-providing nutrients and breast cancer.

This nested case-control study conducted within a large dietary cohort study examined whether recall bias could explain the inconsistent results obtained in case-control and cohort studies of the association between dietary fat and breast cancer. Cases were defined as women diagnosed with breast cancer between 1982 and 1987 who had completed a self-administered food frequency questionnaire on enrollment in the cohort study between 1982 and 1985. They were matched to two controls each, and the study subjects were asked in 1988 to complete a second diet questionnaire addressing their diets at the time of enrollment. The mean nutrient intakes for 325 cases who completed the first diet questionnaire six months or more before breast cancer diagnosis and their 628 matched controls were very similar for the prospectively and retrospectively collected diet questionnaires. There was little difference in the magnitude of the odds ratios estimated from the two questionnaires for the association between breast cancer risk and these nutrients. These data do not provide evidence for recall bias in retrospectively collected nutrient data from breast cancer cases compared with their matched controls.     

An interview strategy was critical for obtaining valid information on the use of hormone replacement therapy

OBJECTIVE: We compared telephone reports of hormone replacement therapy (HRT) use to claims for drugs dispensed. STUDY DESIGN AND SETTING: The study subjects included 106 women who were dispensed HRT and 107 who were not dispensed HRT. RESULTS: Recall of drug use overall was relatively good (65/79=82.3%, 95% confidence interval [CI] 73.9-90.7). Agreement between recall of drug name and the claims for dispensed drugs was lower (61/79=77.2%, 95% CI 68.0-86.5). Of 65 women reporting use of HRT in response to the indication prompt, nine (13.8%) could not identify the drug name using the drug list prompt, but all 65 women identified a drug using the photo prompt. Recall of start date of drug use was poor (29.2% agreement on month/year; 45.8% agreement within 1 month), and recall of end date of drug use was poorer yet (7.7% agreement on month/year; 21.5% agreement within 1 month). CONCLUSION: Recall of drug use and drug names is far better than recall of dates of use. Recall can be enhanced with lists of drug names and color photos, but even with memory prompts, recall remains imperfect. If drug use is the primary exposure of interest in a study, considerable effort is needed to collect it correctly. If not, then perhaps drug histories should be omitted.