Information bias in a case-referent study on mental retardation and parental occupation: colleagues as dual respondents

We conducted a validity study to assess whether information bias from differential misclassification of occupational exposures occurred in a case-referent study on mental retardation and parental occupation. The colleagues of 42 case parents and 38 referent parents were traced and interviewed with a questionnaire similar to that used for the parents. Within each parent-colleague pair, Cohen's kappa coefficient was calculated as a measure of agreement between the reported occupational exposures. Averaged across pairs, the mean kappa coefficient was 0.48 (95% CI = 0.40-0.56) for case pairs and 0.46 (95% CI = 0.38-0.54) for referent pairs, indicating little evidence for differential reporting of exposures between cases and referents. Our results also indicate that colleagues are eligible substitute respondents for information on occupational exposures.     

Assessing consumption of high-fat foods: the effect of grouping foods into single questions.

Questionnaires on the frequency of consumption of foods are commonly used to measure dietary intake in epidemiologic research. To reduce the burden on respondents, questionnaires are often shortened by combining inquiries on similar foods into a single question. The effect of this practice on the reporting of dietary intake has never been investigated, however. To address this issue, we used two food frequency questionnaires in a telephone survey designed to rank adult residents of Alabama by their intake of dietary fat. One questionnaire included 29 questions about separate high-fat foods, whereas the other grouped these same foods into 14 questions. Compared with the 443 respondents interviewed using the 29-item separated-foods questionnaire, the 465 respondents responding to the 14-item grouped-foods questionnaire reported lower average intakes of the foods. In addition, a substantially higher percentage of respondents to the grouped-foods questionnaire reported never consuming the foods.     

Occupational case-control studies: I. Collecting information on work histories and work-related exposures

The strength and credibility of evidence from occupational case-control studies largely depend on the validity and precision with which the work history is reported and the exposure is assessed. We discuss the two steps which ultimately lead to an exposure decision. The first step involves the exchange between the respondent and an interviewer. The latter is usually naïve to occupations and workplace exposures and, as such, is limited to asking generic and open-ended questions about the workplace. Often, this type of information is too nonspecific to assess exposure. In the second step, an expert reviews the information reported on each occupation and decides on exposure status without contacting either the interviewer or respondent. Exposure assessment is not, therefore, integrated with data collection and, in fact, is usually not initiated until after all the interviews are completed. As such, the exposure expert does not have an opportunity to resolve questions before making the exposure decision. To improve the quality and specificity of data collected, we have developed over 40 sets of close-ended questions (branch questions) which are specific to defined occupations. These branch questions, incorporated into a computer-assisted telephone interview, are asked if selected occupations or their synonyms are reported. Second, to link the data collection process with the assessment process, we have developed a procedure called SCORE (Subject Corrected Occupational Report) which provides the industrial hygienist with a cost efficient method to ask questions directly of respondents. Shortly after each interview is completed, a computerized version of the work history is reviewed by the industrial hygienist who develops questions when more information is needed. Subsequently, respondents are mailed a form listing their reported work history along with the questions. After two mailings, 73% of participants in a pilot study returned the SCORE form.     

Assessment of occupational exposure in a population based case-control study: comparing postal questionnaires with personal interviews.

BACKGROUND: In case-control studies, data collection on occupational exposures by means of personal interviews is usually costly and time consuming. As detailed semiquantitative information on exposure from these interviews often has to be dichotomised in the analyses due to the small numbers of exposed subjects, the question is raised whether simple postal questionnaires yield the same results for occupational exposure in epidemiological studies as job specific personal interviews. METHODS: Data on occupational exposures during pregnancy were compared from 121 women who both completed a checklist with 17 occupational exposure categories in a postal questionnaire and were personally interviewed with specific questions on exposure with details of job and task. kappa Coefficients were calculated as measures of agreement corrected for chance, and sensitivity and positive predictive values as measures of validity and usefulness, with the exposure assessment based on information from the interview as the gold standard. RESULTS: Values of kappa varied from 0.09 for domestic cleaning agents to 0.70 for pesticides, indicating only low to moderate agreement between the questionnaire and the interview. Sensitivity ranged from 38% to 100%, with the highest values for agents used by healthcare workers. Positive predictive values were lower, between 9% and 63%, which indicates that overreporting was more common than underreporting in the questionnaire. CONCLUSIONS: These results underline the high potential for misclassification of occupational exposure in studies based on questionnaires. Therefore, postal questionnaires are not considered an alternative to job and task specific personal interviews in epidemiological studies.     

‘DOES THE MODE MATTER?’ - A COMPARISON OF THREE MODES OF QUESTIONNAIRE COMPLETION

This paper includes a brief outline of the research literature on comparisons of different modes of questionnaire completion (face to face, telephone, self-administered), and the results of a pilot study which used a questionnaire to obtain data on maternal experiences and exposures to drugs and environmental agents during pregnancy. Questionnaires were completed for the three modes and comparisons made of the quality of the data and the actual responses obtained. The findings suggest that when using a highly structured questionnaire, and where a favourable rapport has been established between the researcher and the respondents, there are few differences between the modes in those aspects examined in this study.     

Bias in studies of parental self-reported occupational exposure and childhood cancer

Several case-control studies have demonstrated positive associations between parental occupational exposures and childhood cancer. However, an overestimation of risk estimates due to recall bias is of concern. The magnitude and nature of this bias were explored using data from a German case-control study on childhood leukemia conducted between 1992 and 1997. A moderate overreporting of occupational exposures by fathers was observed, particularly for the prenatal period. Overreporting was most apparent when the time between exposure and interview was short. It was also found that job titles were no satisfactory substitute for information on specific occupational exposures. The results of this analysis emphasize the need for more sophisticated exposure assessment methods in epidemiologic studies of childhood cancer. However, because future case-control studies will at least partially rely on questionnaire data, improvements including probing questions, better interview techniques, and validation studies are indicated.     

Proxy respondents and the validity of occupational and other exposure data. The Selected Cancers Cooperative Study Group.

As part of a multicenter cancer case-control study conducted in 1984-1988, a proxy interview was attempted for all cases who were initially interviewed for the study but who died during the 4-year data collection period. To assess the validity of using wives, other relatives, or other informants to obtain information about a subject, the authors compared occupational and other exposure data obtained from 270 male cancer cases and their proxy respondents. The primary focus of the case-control study was on Vietnam military service and exposure to phenoxy herbicides, but cases and their proxy respondents were also asked about occupational and other exposures relevant to the cancers. The accuracy of reporting for specific occupational exposures (e.g., asbestos and formaldehyde) and specific occupations (e.g., dry cleaning and meat packing or processing) was poor, although the latter improved somewhat when only case-spouse pairs were examined. Similarly, there was poor sensitivity in the reporting of herbicide exposure information in farming and other related occupations. In contrast, the reporting of certain demographic characteristics, childhood history characteristics, and use of alcohol and cigarettes was relatively good, and was even better when only case-spouse pairs were examined. The poor quality of proxy information for detailed exposure information suggests the need for careful use and interpretation of proxy information in epidemiologic studies.     

Development and implementation of an environmental risk map for the prevention of occupational accidents in an intensive care unit at a university hospital

This study has the objective to discuss some questions related to occupational risks that health professionals are exposed to in the Intensive Care Unit environment. A questionnaire was used, asking the health care workers to describe the occupational risks they know about. As a result, the participants indicated risks related to biological, physical, chemical, ergonomic and occupational risks.     

Role perceptions and clinical reasoning of community health occupational therapists undertaking home visits

This paper presents the findings of a survey that aimed to: (i) describe the work of metropolitan Community Health Occupational Therapists (CHOTs) in Victoria; and (ii) to obtain basic information regarding the clinical reasoning CHOTs use during home visit assessments. Based on a literature review and clinical experience, a questionnaire was designed to elicit information about CHOT role perceptions and clinical reasoning. Questionnaires were mailed to all 50 CHOTs in metropolitan Melbourne. Thirty-six responses were received (a response rate of 72%). Exploratory data analysis procedures were used to summarize the demographic data and closed questions. A series of open-ended questions and four case scenarios were analysed qualitatively. The findings indicated that the majority of community health occupational therapists were mature in age, widely experienced, and client centred in their diverse practice roles. Generally, they were highly confident of their skills in client-related tasks and enjoyed the main components of their roles, particularly home visiting. Participant responses to the four case scenarios indicated that they used procedural, interactive and conditional reasoning to identify the most important factors to consider, the action they would take, and whether they would see the client again. In conclusion, while the findings of this survey provide an overview of CHOT work in Victoria, further studies are urgently required to explore the clinical reasoning that supports this aspect of occupational therapy practice.     

Intelligent database generated occupational questionnaire system

Obtaining an adequate occupational history requires special expertise to "ask the right questions" that are relevant to a particular patient's specific health conditions and potential exposures. This article describes a way to systematically accomplish this by means of a computer system that can overcome limited availability of necessary clinical occupational health expertise. The Intelligent Questionnaire system is a computer-based system for generating case-specific questionnaires about the influence of work on respiratory disease. Intelligent Questionnaire includes three databases: Questions, Responses, and Calls (clues to identify questions). The Questionnaire also arranges questions in a logical manner and provides a customized data entry screen for each subject. This approach provides primary practitioners with expertise on a case-by-case basis. It also facilitates occupational health surveillance because it allows acquiring detailed case-specific information in a systematic fashion. A computer-based system can facilitate obtaining occupational histories with high specificity and consistency without depending on general availability of a human occupational health clinical expertise.     

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.     

Attitudes of young people with diabetes to an Internet-based virtual clinic

We assessed the feasibility of developing a virtual diabetes clinic for young people, using the Internet. The proposed content of the site would be based on self-efficacy theory, aiming to develop confidence in self-management of diabetes. A questionnaire about the proposed Website was delivered to 72 patients who attended a young person's outpatient clinic in a district hospital. Thirty-nine replies were received, a response rate of 54%. The mean age of the respondents was 13 years. A positive attitude to the potential clinic was reported by 95% of respondents. The items rated as most useful were: quick and easy access to up-to-date information about diabetes; the opportunity to ask an expert; good graphics; easy navigation; interactivity. Responses to open questions indicated that 24-hour access and anonymity in asking questions were also valued. A virtual clinic appears to be a possible method of health-care delivery to young people with diabetes.     

Occupational exposures to influenza among healthcare workers in the United States

The objective of this study is to estimate the annual number of occupational exposures to influenza among healthcare workers that result from providing direct and supportive care to influenza patients in acute care, home care and long-term care settings. Literature review was used to identify healthcare utilization for influenza, and worker activity patterns. This information was used, with Monte Carlo simulation, to tabulate the mean annual number of occupational exposures. Given a medium-sized epidemic with a 6% annual symptomatic influenza incidence proportion, the mean number of occupational exposures was estimated to be 81.8 million annually. Among the approximately 14 million healthcare workers, this corresponds to 5.8 exposures per worker annually, on average. Exposures, however, are likely concentrated among subsets of healthcare workers. Occupational exposures were most numerous in ambulatory care settings (38%), followed by long-term care facilities (30%) and home care settings (21%). The annual number of occupational exposures to influenza is high, but not every occupational exposure will result in infection. Some infection control activities, like patient isolation, can reduce the number of occupational exposures.     

Ascertainment of pesticide exposures of migrant and seasonal farmworker children: findings from focus groups.

BACKGROUND: To design questionnaires for epidemiologic research among children of migrant farmworkers, researchers need to consider ways to best solicit information about pesticide exposures. METHODS: Bilingual facilitators conducted five focus groups with either migrant farmworker mothers or their children (age range 8-16 years) in southern Texas and northeastern Colorado. Guided questions were used to assess activities of migrant farmworker children and the ways to best elicit information about exposure to pesticides. RESULTS: Participants reported a large number of activities that may potentially expose children to pesticides through both direct and indirect routes. Prompting, indirect questions about chemical use, and use of local and trusted facilitators increased information elicited from focus group participants. CONCLUSIONS: These focus groups helped to provide information for developing questionnaire items related to pesticide exposure among migrant farmworker children, and highlighted the importance of using bilingual community interviewers and including children as respondents.     

Occupational dust exposure and the risk of laryngeal cancer in Turkey

OBJECTIVES: A hospital-based case-referent study was conducted to identify occupational risk factors for laryngeal cancer. In a previous report an association was found between laryngeal cancer and occupations with potential dust exposure; a job-exposure matrix was developed to aid further evaluation of laryngeal cancer risks from five occupational dust exposures. METHODS: Among 7631 cancer cases from the Okmeydani Hospital, Istanbul, between 1979 and 1984, 958 larynx cancer cases were identified among men. After exclusions, 940 laryngeal cancer cases and 1519 referents were available. A standardized questionnaire was used to obtain basic information on the patients. Seven-digit standard occupational and industrial codes were created to classify the job and industrial titles. A job-exposure matrix was developed for occupational dusts, including silica, asbestos, wood, cotton, and grain, and age-, smoking-, and alcohol-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were calculated to evaluate risks of laryngeal cancer. RESULTS: An excess of laryngeal cancer occurred for workers potentially exposed to silica and cotton dust, particularly for supraglottic cancer (OR 1.8, 95% CI 1.3-2.3, for silica and OR 1.6, 95% CI 1.1-2.5, for cotton dust), and there was a significant dose-response relationship with silica exposure. No relationship was found between laryngeal cancer and asbestos, grain, or wood dust exposures. CONCLUSION: Laryngeal cancer, especially supraglottic tumors, is associated with silica and cotton dust exposures in Turkey.     

Childhood social class and cancer incidence: results of the globe study

Despite increased recognition of the importance of investigating socio-economic inequalities in health from a life course perspective, little is known about the influence of childhood socio-economic position (SEP) on cancer incidence. The authors studied the association between father's occupation and adult cancer incidence by linking information from the longitudinal GLOBE study with the regional population-based Eindhoven Cancer Registry (the Netherlands) over a period of 14 years. In 1991, 18,973 participants (response rate 70.1%) of this study responded to a postal questionnaire, including questions on SEP in youth and adulthood. Respondents above the age of 24 were included (N=12,978). Cox regression was used to calculate hazard ratios (HR) for all cancers as well as for the five most frequently occurring cancers by respondent's educational level or occupational class, and by father's occupational class (adjusted for respondent's education and occupation). Respondents with a low educational level showed an increased risk of all cancers, lung and breast cancer (in women). Respondents with a low adult occupational level showed an increased risk of lung cancer and a reduced risk of basal cell carcinoma. After adjustment for adult education and occupation, respondents whose father was in a lower occupational class showed an increased risk of colorectal cancer as compared to those with a father in the highest social class. In contrast, respondents whose father was in a lower occupational class, showed a decreased risk of basal cell carcinoma as compared to those with a father in the highest occupational class. The association between childhood SEP and cancer incidence is less consistent than the association between adult SEP and cancer incidence, but may exist for colorectal cancer and basal cell carcinoma.     

Cardiovascular malformations, work attendance, and occupational exposures during pregnancy in Finland

To explore for associations between occupational factors and cardiovascular malformations, information on the parents of 160 infants with cardiovascular malformations and 160 control parents was studied. The case infants had been reported consecutively to the Finnish Register of Congenital Malformations. All mothers were interviewed identically after delivery, using both open and pro forma questions about detailed work tasks, exposures, and leisure activities during pregnancy. The interview information was evaluated blindly. Neither parental occupational titles nor maternal working per se gave new clues to the teratogenic risk; nor did shift working, wearing of personal protective equipment, or the mother's own opinion on exposures during pregnancy. Identified occupational exposures, as categorized by an industrial hygienist, showed no remarkable associations to cardiovascular malformations. Few mothers were exposed substantially to specific occupational hazards. Comparing mothers who used medications in the first trimester with those who did not showed an odds ratio of 2.2 (95% confidence interval 1.3-3.9) when adjusted for potential confounding by multivariate logistic methods.     

A survey of utilization of and problems with the MSDS in chemical substances management at workplaces in Kanagawa Prefecture]

Kanagawa Occupational Health Promotion Center conducted a survey on how the MSDS is utilized at workplaces with more than 50 employees handling chemical substances, and what measures are taken to help employees to thoroughly understand information in the Material Safety Data Sheet (MSDS). Questionnaires were sent out to 265 enterprises in Kanagawa prefecture, putting questions to industrial physicians and industrial hygiene supervisors. The objective of the survey was to find out how MSDS is adopted in the system to manage occupational health, what improvements the survey respondents want in MSDS and what expectations the respondents have of our center. 193 enterprises (72.8%) returned answers to the questionnaire. The major findings are as follows. (1) In many companies, information on hazardous/toxic materials is "controlled by a division using such materials", and roughly half of the companies have compiled a common list shared throughout the company. (2) For the most part suppliers submit to the MSDS. Larger companies have a higher rate of posting up or filing the MSDS at their workplaces. Only 25.8% of the companies "rewrite the MSDS so that workers can understand it." (3) Companies that carry out a hazard/toxicity assessment before introducing a new chemical substance account for 72.1%, which is higher than we expected. It indicates that even though the companies don't manage the MSDS adequately, they are highly concerned about hazard control of chemical substances. (4) The rate of answering that "the current MSDS is not easy to understand" is higher among large-sized enterprises and lower among enterprises with fewer than 300 employees. (5) Asked what improvement needs to be made on the MSDS, the industrial physicians and industrial hygiene supervisors gave same answers such as "Workers find the terminology difficult to understand." and "Levels of toxicity can't be clearly identified." (6) The respondents expect our center to provide information for the MSDS. In conclusion, it is considered that in order to prepare understandable MSDSs to workers in enterprises, the role of our center to provide information and education on the MSDS to respondents was important.     

Chronic non-specific lung disease and occupational exposures estimated by means of a job exposure matrix: the Zutphen Study

Information gathered in the Zutphen Study, the Dutch contribution to the Seven Countries Study that started in the 1960s, was used in this study. Of the 1266 men invited to take part in the 1985 survey, 939 (74%) participated. All participants were interviewed according to the BMRC chronic non-specific lung disease (CNSLD) questionnaire and medically examined for CNSLD complaints by a trained physician. The physician also filled in a questionnaire containing questions concerning previous treatments for asthma, bronchitis and emphysema. Exposures were generated by means of a job exposure matrix on the basis of the longest performed job and the gain and grouped into 12 exposure categories. A logistic regression analysis was performed using the occupational exposures as the sector of industry dependent variables in allowing for smoking habits, age and socioeconomic status. For the diagnosis by the physician and treatment for emphysema and or bronchitis, the strongest elevated odds ratios were found, indicating an adverse effect of the occupational exposures. In contrast, the variable 'ever treated for asthma' had odds ratios smaller than one with most of the exposure variables indicating a selection effect. In an analysis in which everyone who was ever treated for asthma was excluded an increase in the odds ratios compared with the first analysis was seen. The relationships between occupational exposures as generated by the job exposure matrix and CNSLD were stronger than those recently reported in the literature.