Validation of mobile phone use recall in the multinational MOBI‐kids study

Potential differential and non‐differential recall error in mobile phone use(MPU) in the multinational MOBI‐Kids case–control study were evaluated.We compared self‐reported MPU with network operator billing record data up to 3 months, 1 year, and 2 years before the interview date from 702subjects aged between 10 and 24 years in eight countries. Spearman rankcorrelations, Kappa coefficients and geometric mean ratios (GMRs) wereused. No material differences in MPU recall estimates between cases andcontrols were observed. The Spearman rank correlation coefficientsbetween self‐reported and recorded MPU in the most recent 3 monthswere 0.57 and 0.59 for call number and for call duration, respectively. Thenumber of calls was on average underestimated by the participants(GMR = 0.69), while the duration of calls was overestimated (GMR = 1.59).Country, years since start of using a mobile phone, age at time of interview,and sex did not appear to influence recall accuracy for either call number orcall duration. A trend in recall error was seen with level of self‐reportedMPU, with underestimation of use at lower levels and overestimation of useat higher levels for both number and duration of calls. Although bothsystematic and random errors in self‐reported MPU among participantswere observed, there was no evidence of differential recall error betweencases and controls. Nonetheless, these sources of exposure measurementerror warrant consideration in interpretation of the MOBI‐Kids case–controlstudy results on the association between children's use of mobile phonesand potential brain cancer risk

Knowledge and use of emergency contraception among women in the Western Cape province of South Africa: a cross-sectional study

BACKGROUND: Emergency contraception (EC) is widely available free of charge at public sector clinics in South Africa. At the same time, rates of teenage and unintended pregnancy in South Africa remain high, and there are few data on knowledge of EC in the general population in South Africa, as in other resource-limited settings. METHODS: We conducted a cross-sectional, interviewer-administered survey among 831 sexually active women at 26 randomly selected public sector clinics in the Western Cape province. RESULTS: Overall, 30% of the women had ever heard of EC when asked directly, after the method was described to them. Only 15% mentioned EC by name or description spontaneously. Knowledge of EC was independently associated with higher education, being married, and living in an urban setting. Four percent of women had ever used EC. DISCUSSION: These data suggest that knowledge of EC in this setting is more common among women of higher socioeconomic status living in urban areas. For EC to play a role in decreasing unintended pregnancy in South Africa, specific interventions are necessary to increase knowledge of the method, where to get it, and the appropriate time interval for its use before the need for EC arises. Future health promotion campaigns should target rural and low socioeconomic status communities

Anemia, Weight Status, and Fatigue Among Farmworkers in California

ObjectiveThis study aimed to determine the prevalence of anemia and overweight/obesity and assess the relationships between hematocrit (Hct) and body mass index (BMI), and between fatigue and Hct, among a sample of farmworkers in California.MethodsWe estimated the prevalence of anemia (using Hct), overweight/obesity (BMI ≥25 kg/m 2 ), and self-reported fatigue in 587 farmworkers. Multivariable linear and logistic regression models were used to examine the associations between Hct and BMI, and between fatigue and Hct.ResultsAnemia prevalence was 3.1%, overweight/obesity prevalence was 80.7%, and 78% of workers reported fatigue at work. There was no association between Hct and BMI or between Hct and reported fatigue. Women were more likely than men to have lower Hct and higher BMI.ConclusionsA majority of farmworkers in this sample were overweight/obese, but anemia was uncommon. Anemia among more vulnerable subgroups of farmworkers should be explored

How Does Environmental Temperature Affect Farmworkers' Work Rates in the California Heat Illness Prevention Study?

ObjectiveEstimate the association between environmental temperature (wet bulb globe temperature [WBGT]) and work rate over the course of a workday.MethodsRepeated-measures regression was used to identify characteristics impacting work rate in a cross-sectional study of Latino farmworkers. Minute-by-minute work rate (measured by accelerometer) and WBGT were averaged over 15-minute intervals.ResultsWork rate decreased by 4.34 (95% confidence interval [CI], -7.09 to -1.59) counts per minute per degree Celsius WBGT in the previous 15-minute interval. Cumulative quarter hours worked (2.13; 95% CI, 0.82 to 3.45), age (-3.64; 95% CI, -4.50 to -2.79), and dehydration at the end of workday (51.37; 95% CI, 19.24 to 83.50) were associated with counts per minute as were gender, pay type (piece rate vs hourly) and body mass index ≥25 kg/m 2 . The effects of pay type and body mass index were modified by gender.ConclusionIncreased temperature was associated with a decrease in work rate

Nonparticipation Selection Bias in the MOBI-Kids Study

BACKGROUND: MOBI-Kids is a 14-country case-control study designed to investigate the potential effects of electromagnetic field exposure from mobile telecommunications devices on brain tumor risk in children and young adults conducted from 2010 to 2016. This work describes differences in cellular telephone use and personal characteristics among interviewed participants and refusers responding to a brief nonrespondent questionnaire. It also assesses the potential impact of nonparticipation selection bias on study findings. METHODS: We compared nonrespondent questionnaires completed by 77 cases and 498 control refusers with responses from 683 interviewed cases and 1501 controls (suspected appendicitis patients) in six countries (France, Germany, Israel, Italy, Japan, and Spain). We derived selection bias factors and estimated inverse probability of selection weights for use in analysis of MOBI-Kids data. RESULTS: The prevalence of ever-regular use was somewhat higher among interviewed participants than nonrespondent questionnaire respondents 10-14 years of age (68% vs. 62% controls, 63% vs. 48% cases); in those 20-24 years, the prevalence was ≥97%. Interviewed controls and cases in the 15- to 19- and 20- to 24-year-old age groups were more likely to have a time since start of use of 5+ years. Selection bias factors generally indicated a small underestimation in cellular telephone odds ratios (ORs) ranging from 0.96 to 0.97 for ever-regular use and 0.92 to 0.94 for time since start of use (5+ years), but varied in alternative hypothetical scenarios considered. CONCLUSIONS: Although limited by small numbers of nonrespondent questionnaire respondents, findings generally indicated a small underestimation in cellular telephone ORs due to selective nonparticipation