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 702 subjects aged between 10 and 24 years in eight countries. Spearman rank correlations, Kappa coefficients and geometric mean ratios (GMRs) were used. No material differences in MPU recall estimates between cases and controls were observed. The Spearman rank correlation coefficients between self-reported and recorded MPU in the most recent 3 months were 0.57 and 0.59 for call number and for call duration, respectively. The number 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 or call duration. A trend in recall error was seen with level of self-reported MPU, with underestimation of use at lower levels and overestimation of use at higher levels for both number and duration of calls. Although both systematic and random errors in self-reported MPU among participants were observed, there was no evidence of differential recall error between cases and controls. Nonetheless, these sources of exposure measurement error warrant consideration in interpretation of the MOBI-Kids case-control study results on the association between children's use of mobile phones and potential brain cancer risk.

Patients' and health care providers' perspectives on quality of hemophilia care in the Netherlands: a questionnaire and interview study.

Background: Hemophilia care has improved greatly because of advances in treatment options and comprehensive care. In-depth insight into the perspectives of persons with hemophilia and health care providers on their care may provide targets for further improvements. Objectives: To assess satisfaction of the hemophilia population with their care, to explore factors determining care satisfaction, and to identify areas for potential health care improvements, including digital health tools. Methods: First, to assess care satisfaction and factors determining satisfaction and health care improvements, data from a nationwide, cross-sectional questionnaire among 867 adult and pediatric Dutch persons with hemophilia A or B were analyzed. This included the Hemophilia Patient Satisfaction Scale questionnaire, Canadian Hemophilia Outcomes Kids' Life Assessment Tool satisfaction questions, a visual analog scale satisfaction score, and open questions. Second, to further explore factors determining satisfaction and health care improvements, semistructured interviews were conducted with 19 persons with hemophilia or their parents and 18 health care providers. Results: High care satisfaction was found, with an overall median Hemophilia Patient Satisfaction Scale score of 12 (IQR, 6-21). Participants in the interviews reported that patient-professional interactions, availability of care, and coordination of care were major factors determining satisfaction. Suggested health care improvements included improved information provision and coordination of care, especially shared care with professionals not working within comprehensive care centers. Participants suggested that digital health tools could aid in this. Conclusion: Satisfaction with hemophilia care is high among persons with hemophilia in the Netherlands, although several potential improvements have been identified. Accentuating these is especially relevant in the current era of treatment innovations, in which we might focus less on other aspects of care.

Recall of mobile phone usage and laterality in young people: The multinational Mobi-Expo study.

OBJECTIVE: To study recall of mobile phone usage, including laterality and hands-free use, in young people. METHODS: Actual mobile phone use was recorded among volunteers aged between 10 and 24 years from 12 countries by the software application XMobiSense and was compared with self-reported mobile phone use at 6 and 18 months after using the application. The application recorded number and duration of voice calls, number of text messages, amount of data transfer, laterality (% of call time the phone was near the right or left side of the head, or neither), and hands-free usage. After data cleaning, 466 participants were available for the main analyses (recorded vs. self-reported phone use after 6 months). RESULTS: Participants were on average 18.6 years old (IQR 15.2-21.8 years). The Spearman correlation coefficients between recorded and self-reported (after 6 months) number and duration of voice calls were 0.68 and 0.65, respectively. Number of calls was on average underestimated by the participants (adjusted geometric mean ratio (GMR) self-report/recorded = 0.52, 95% CI = 0.47-0.58), while duration of calls was overestimated (GMR=1.32, 95%, CI = 1.15-1.52). The ratios significantly differed by country, age, maternal educational level, and level of reported phone use, but not by time of the interview (6 vs. 18 months). Individuals who reported low mobile phone use underestimated their use, while individuals who reported the highest level of phone use were more likely to overestimate their use. Individuals who reported using the phone mainly on the right side of the head used it more on the right (71.1%) than the left (28.9%) side. Self-reported left side users, however, used the phone only slightly more on the left (53.3%) than the right (46.7%) side. Recorded percentage hands-free use (headset, speaker mode, Bluetooth) increased with increasing self-reported frequency of hands-free device usage. Frequent (≥50% of call time) reported headset or speaker mode use corresponded with 17.1% and 17.2% of total call time, respectively, that was recorded as hands-free use. DISCUSSION: These results indicate that young people can recall phone use moderately well, with recall depending on the amount of phone use and participants' characteristics. The obtained information can be used to calibrate self-reported mobile use to improve estimation of radiofrequency exposure from mobile phones.

Patterns of cellular phone use among young people in 12 countries: Implications for RF exposure.

Characterizing exposure to radiofrequency (RF) fields from wireless telecommunications technologies during childhood and adolescence is a research priority in investigating the health effects of RF. The Mobi-Expo study aimed to describe characteristics and determinants of cellular phone use in 534 young people (10-24years) in 12 countries. The study used a specifically designed software application installed on smartphones to collect data on the use of wireless telecommunications devices within this age group. The role of gender, age, maternal education, calendar period, and country was evaluated through multivariate models mutually adjusting for all variables. Call number and duration were higher among females compared to males (geometric mean (GM) ratio 1.17 and 1.42, respectively), among 20-24year olds compared to 10-14year olds (GM ratio 2.09 and 4.40, respectively), and among lowest compared to highest social classes (GM ratio 1.52 and 1.58, respectively). The number of SMS was higher in females (GM ratio 1.46) and the middle age group (15-19year olds: GM ratio 2.21 compared to 10-14year olds) and decreased over time. Data use was highest in the oldest age group, whereas Wi-Fi use was highest in the middle age group. Both data and Wi-Fi use increased over time. Large differences in the number and duration of calls, SMS, and data/Wi-Fi use were seen by country, with country and age accounting for up to 50% of the variance. Hands-free and laterality of use did not show significant differences by sex, age, education, study period, or country. Although limited by a convenience sample, these results provide valuable insights to the design, analysis, and interpretation of future epidemiological studies concerning the health effects of exposure resulting from cellular phone use in young people. In addition, the information provided by this research may be used to design strategies to minimize RF exposure.

Validating self-reported mobile phone use in adults using a newly developed smartphone application.

OBJECTIVE: Interpretation of epidemiological studies on health effects from mobile phone use is hindered by uncertainties in the exposure assessment. We used a newly developed smartphone application (app) to validate self-reported mobile phone use and behaviour among adults. METHODS: 107 participants (mean age 41.4 years) in the Netherlands either downloaded the software app on their smartphone or were provided with a study smartphone for 4 weeks. The app recorded the number and duration of calls, text messages, data transfer, laterality and hands-free use. Self-reported mobile phone use was collected before using the app and after 6 months through an interviewer-administered questionnaire. RESULTS: The geometric mean ratios (GMR, 95% CI) and Spearman correlations (r) of self-reported (after 6 months) versus recorded number and duration of calls were: GMR=0.65 (0.53 to 0.80), r=0.53; and GMR=1.11 (0.86 to 1.42), r=0.57 respectively. Participants held the phone on average for 86% of the total call time near the head. Self-reported right side users held the phone for 70.7% of the total call time on the right side of the head, and left side users for 66.2% on the left side of the head. The percentage of total call time that the use of hands-free devices (headset, speaker mode, Bluetooth) was recorded increased with increasing frequency of reported hands-free device usage. DISCUSSION: The observed recall errors and precision of reported laterality and hands-free use can be used to quantify and improve radiofrequency exposure models based on self-reported mobile phone use.

Using software-modified smartphones to validate self-reported mobile phone use in young people: A pilot study.

A newly developed smartphone application was piloted to characterize and validate mobile phone use in young people. Twenty-six volunteers (mean age 17.3 years) from France, Spain, and the Netherlands used a software-modified smartphone for 4 weeks; the application installed on the phone recorded number and duration of calls, data use, laterality, hands-free device usage, and communication system used for both voice calls and data transfer. Upon returning the phone, participants estimated their mobile phone use during those 4 weeks via an interviewer-administered questionnaire. Results indicated that participants on average underestimated the number of calls they made, while they overestimated total call duration. Participants held the phone for about 90% of total call time near the head, mainly on the side of the head they reported as dominant. Some limitations were encountered when comparing reported and recorded data use and speaker use. When applied in a larger sample, information recorded by the smartphone application will be very useful to improve radiofrequency (RF) exposure modeling from mobile phones to be used in epidemiological research.

Maternal early-pregnancy vitamin D status is associated with maternal depressive symptoms in the Amsterdam Born Children and Their Development cohort.

OBJECTIVE: To examine low maternal vitamin D status as a potential risk factor for high levels of depressive symptoms in a pregnant population. METHODS: In the Amsterdam Born Children and Their Development cohort, maternal serum vitamin D (n = 4236) was measured during early pregnancy (median, 13 weeks) and labeled "deficient" (≤ 29.9 nM), "insufficient" (30-49.9 nM), "sufficient" (50-79.9 nM), and "normal" (≥ 80 nM). Maternal depressive symptoms were measured by the Center for Epidemiological Studies Depression Scale at 16-week gestation. The association of vitamin D status with high levels of depressive symptoms (Center for Epidemiological Studies Depression score ≥ 16) was assessed by multivariate logistic regression (final sample, 4101). RESULTS: Overall, 23% of women had vitamin D deficiency, and 21% of women had vitamin D insufficiency. Women with high levels of depressive symptoms (28%) had lower vitamin D concentrations than women with low levels of depressive symptoms (p < .001). After adjustment for constitutional factors, life-style and psychosocial covariates, and sociodemographic factors, vitamin D deficiency (odds ratio [OR], 1.48; 95% confidence interval [CI], 1.13-1.95) and insufficiency (OR, 1.44; 95% CI, 1.12-1.85) were significantly associated with high levels of depressive symptoms. Additional analyses revealed a linear trend, with an OR of 1.05 (95% CI, 1.02-1.08) for each 10-nM decrease in vitamin D status. CONCLUSIONS: In this study, low early-pregnancy vitamin D status was associated with elevated depressive symptoms in pregnancy. Further research, using a randomized controlled design, would be required to confirm the causality of this association and the potential benefits of higher vitamin D intake for psychosocial health.

Maternal vitamin B-12 and folate status during pregnancy and excessive infant crying.

BACKGROUND: The etiology of excessive infant crying is largely unknown. We hypothesize that excessive infant crying may have an early nutritional origin during fetal development. AIMS: This study is the first to explore whether (1) maternal vitamin B-12 and folate status during pregnancy are associated with excessive infant crying, and (2) whether and how maternal psychological well-being during pregnancy affects these associations. STUDY DESIGN: Women were approached around the 12th pregnancy week to complete a questionnaire (n=8266) and to donate a blood sample (n=4389); vitamin B-12 and folate concentrations were determined in serum. Infant crying behavior was measured through a postpartum questionnaire (±3 months; n=5218). SUBJECTS: Pregnant women living in Amsterdam and their newborn child. OUTCOME MEASURES: Excessive infant crying, defined as crying ≥3 h/day on average in the past week. RESULTS: Multiple logistic regression analysis was performed for 2921 (vitamin B-12) and 2622 (folate) women.Vitamin B-12 concentration (categorized into quintiles) was associated with excessive infant crying after adjustment for maternal age, parity, ethnicity, education, maternal smoking and psychological problems (OR[95%CI]: Q1=3.31[1.48-7.41]; Q2=2.50[1.08-5.77]; Q3=2.59[1.12-6.00]; Q4=2.77[1.20-6.40]; Q5=reference). Stratified analysis suggested a stronger association among women with high levels of psychological problems during pregnancy. Folate concentration was not associated with excessive infant crying. CONCLUSIONS: First evidence is provided for an early nutritional origin in excessive infant crying. A low maternal vitamin B-12 status during pregnancy could, in theory, affect infant crying behavior through two potential mechanisms: the methionine-homocysteine metabolism and/or the maturation of the sleep-wake rhythm.

Maternal depressive symptoms in relation to perinatal mortality and morbidity: results from a large multiethnic cohort study.

OBJECTIVE: To explore whether 1) maternal depressive symptoms during pregnancy are associated with preterm birth (PTB), small for gestational age (SGA), a low Apgar score and child loss; 2) maternal smoking mediates the associations; and 3) the associations differ by ethnic background. METHODS: Pregnant women in Amsterdam were approached during their first prenatal visit to participate in the Amsterdam Born Children and their Development study. They filled out a questionnaire covering sociodemographic data, life-style, and (psychosocial) health. Depressive symptoms were assessed with the Center for Epidemiologic Studies Depression scale. The baseline sample consisted of 8,052 women; the main ethnic groups were: Dutch, Creole, Turkish, and Moroccan. RESULTS: The prevalence of perinatal outcomes was: 5.4% (PTB); 12.3% (SGA); l 1.5% (low Apgar score); and 1.4% (child loss). The prevalence of high depressive symptomatology was 30.6%. After adjustment for maternal age, parity, education, ethnicity, prepregnancy body mass index, hypertension, alcohol and drug use, and a small mediation effect of maternal smoking, high versus low levels of depressive symptoms were associated with SGA (odds ratio [OR], 1.19; p = .02) and a low Apgar score (OR, 1.74; p = .01), but not with PTB (OR, 1.16; p = .18) and child loss (OR, 1.28; p = .24). Stratified analyses by ethnic background showed a tendency toward higher risks, although insignificant, among Creole women. CONCLUSIONS: Several pathways may explain the detrimental effects of maternal depressive symptomatology on perinatal health outcomes, including a psychoendocrinological pathway involving the hormone cortisol or mediation effects by maternal risk behaviors. Further research should explore the underlying pathways, in particular among ethnic subgroups.

Maternal cortisol and offspring birthweight: results from a large prospective cohort study.

Maternal psychosocial problems may affect fetal growth through maternal cortisol. This large prospective cohort study examined among 2810 women (1) the association of maternal cortisol levels with offspring birthweight and small for gestational age (SGA) risk and (2) the mediating role of maternal cortisol on the relation between maternal psychosocial problems and fetal growth. Pregnant women in Amsterdam were approached during their first prepartum visit (+/-13 weeks gestation). Total maternal cortisol level was determined in serum and maternal psychosocial indicators were collected through a questionnaire. Maternal cortisol levels were negatively related to offspring birthweight (B=-0.35; p<.001) and positively to SGA (OR=1.00; p=.027); after adjustment (for gestational age at birth, infant gender, ethnicity, maternal age, parity, BMI, and smoking), these effects were statistically insignificant. Post hoc analysis revealed a moderation effect by time of day: only in those women who provided a blood sample < or =09:00h (n=94), higher maternal cortisol levels were independently related to lower birthweights (B=-0.94; p=.025) and a higher SGA risk (OR=1.01; p=.032). Maternal psychosocial problems were not associated with cortisol levels. In conclusion, although an independent association between maternal cortisol levels in early pregnancy and offspring birthweight and SGA risk was not observed, exploratory post hoc analysis suggested that the association was moderated by time of day, such that the association was only present in the early morning. The hypothesis that maternal psychosocial problems affect fetal growth through elevated maternal cortisol levels could not be supported.

Psychosocial problems and continued smoking during pregnancy.

The present study examined the association of several psychosocial problems with continued smoking during pregnancy. Based on a population-based cohort study among pregnant women in Amsterdam (n=8266), women who smoked before pregnancy were included in this study (n=1947). Women completed a questionnaire around the 12th week of gestation. Based on whether they smoked in the past week, participants were categorized as quitters or non-quitters. Depressive symptoms (CES-D), anxiety (STAI), pregnancy-related anxiety, job strain, parenting stress and physical/sexual violence were measured. Multiple logistic regression analyses were performed. After adjustment for sociodemographic and smoking-related covariates, low and high levels of pregnancy-related anxiety, exposure to physical/sexual violence, and high job strain were significantly associated with continued smoking during pregnancy. Intensive and comprehensive smoking cessation programs are required for pregnant women, which includes the management of psychosocial problems.

Ethnic differences in term birthweight: the role of constitutional and environmental factors.

It is not clear to what extent ethnic differences in the term birthweight distribution are constitutional or pathological. This study explored term birthweight heterogeneity between ethnic groups and the explanatory role of constitutional and environmental factors. As part of a prospective cohort study, the Amsterdam Born Children and their Development study, 8266 pregnant women filled out a questionnaire during early pregnancy. Ethnic groups were categorised as: native Dutch group; first and second generation Surinamese, Antillean, Turkish, Moroccan, Ghanaian and other non-Dutch groups. Only singleton livebirths with >or=37.0 weeks of gestation and with complete data were included for analysis (n = 7118). We performed linear regression analyses to estimate the association between ethnicity and, for gestational age, standardised birthweight at term, adjusted for constitutional (fetal gender, parity, maternal age, maternal height) and environmental (education, cohabitation status, maternal body mass index, smoking, alcohol consumption, depression, work stress) determinants respectively. Mean birthweight ranged from 3223 g (second generation Surinamese newborns) to 3548 g (Dutch newborns). Adjustment for constitutional factors substantially reduced the ethnic differences in birthweight, while adjustment for environmental factors provided little additional explanation. Surinamese [first generation: regression coefficient (b) = -98.3 g, P < 0.001; second generation: b = -159.3 g, P < 0.001], first generation Antillean (b = -102.0 g, P = 0.037), and Ghanaian newborns (b = -120.7 g, P = 0.001) remained significantly smaller than Dutch newborns after adjustment for all determinants. Term birthweight differences between Dutch newborns and Turkish, Moroccan and other non-Dutch newborns were largely explained by constitutional rather than environmental determinants, limiting the need for prevention. Surinamese, Antillean and Ghanaian (mainly black) newborns remained unexplainably smaller after adjustment, leaving the possibility of either unknown constitutional or pathological underlying mechanisms.