Risk factors for reporting adverse events and for study withdrawal in a population-based trial of vitamin D supplementation.

With increasing numbers of randomized controlled trials (RCTs) investigating potential health events of vitamin D supplementation, a better understanding is required of the risk factors for adverse events and for study withdrawals. This analysis aimed to identify baseline risk factors of reporting an adverse event in a multi-year randomized double-blinded placebo-controlled trial of vitamin D supplementation. The secondary aim was to investigate if adverse events were associated with study withdrawals. We analyzed data from the Vitamin D Assessment (ViDA) study: 5110 adults, aged 50-84 years, living in Auckland, New Zealand. Monthly doses of 100,000 IU vitamin D3 or placebo were mailed to participants homes, with a questionnaire to collect data on adverse events and adherence to the study capsule (initially monthly, then 4-monthly). Median follow-up was 3.3 years. Data were analysed using multivariable log-binomial regression and Cox-regression. During the follow-up period, 818 people reported adverse events and 412 withdrew or stopped returning questionnaires. Vitamin D was not associated with reporting of adverse events. Of sociodemographic factors, ethnicity was associated with reporting adverse events: compared to European participants, Maori and Pacific Islander people were more likely to report an adverse event. Non-smokers were more likely to report an adverse event, compared to smokers (adjusted hazard ratio (HR) = 1.80; 95%CI = 1.24, 2.62); as were those who had reported a history of depression (adjusted HR = 1.27; 95%CI = 1.01, 1.60) or a recent cough or cold (adjusted HR = 1.22; 95%CI = 1.03, 1.44) at baseline. Reporting of adverse events was not associated with withdrawals (adjusted HR = 1.12; 95%CI = 0.86, 1.46). These data did not identify any clear pattern in the factors associated with self-reported adverse events, which themselves did not increase risk of withdrawals.

Arterial waveform parameters in a large, population-based sample of adults: relationships with ethnicity and lifestyle factors.

This corrects the article DOI: 10.1038/jhh.2016.78.

Arterial waveform parameters in a large, population-based sample of adults: relationships with ethnicity and lifestyle factors.

Little is known about how aortic waveform parameters vary with ethnicity and lifestyle factors. We investigated these issues in a large, population-based sample. We carried out a cross-sectional analysis of 4798 men and women, aged 50-84 years from Auckland, New Zealand. Participants were 3961 European, 321 Pacific, 266 Maori and 250 South Asian people. We assessed modifiable lifestyle factors via questionnaires, and measured body mass index (BMI) and brachial blood pressure (BP). Suprasystolic oscillometry was used to derive aortic pressure, from which several haemodynamic parameters were calculated. Heavy alcohol consumption and BMI were positively related to most waveform parameters. Current smokers had higher levels of aortic augmentation index than non-smokers (difference=3.7%, P<0.0001). Aortic waveform parameters, controlling for demographics, antihypertensives, diabetes and cardiovascular disease (CVD), were higher in non-Europeans than in Europeans. Further adjustment for brachial BP or lifestyle factors (particularly BMI) reduced many differences but several remained. Despite even further adjustment for mean arterial pressure, pulse rate, height and total:high-density lipoprotein cholesterol, compared with Europeans, South Asians had higher levels of all measured aortic waveform parameters (for example, for backward pressure amplitude: ß=1.5 mm Hg; P<0.0001), whereas Pacific people had 9% higher loge (excess pressure integral) (P<0.0001). In conclusion, aortic waveform parameters varied with ethnicity in line with the greater prevalence of CVD among non-white populations. Generally, this was true even after accounting for brachial BP, suggesting that waveform parameters may have increased usefulness in capturing ethnic variations in cardiovascular risk. Heavy alcohol consumption, smoking and especially BMI may partially contribute to elevated levels of these parameters.

The utility of serving size in the measurement of soft drink consumption.

BACKGROUND: Many studies examining population differences in soft drink consumption or the association it has with fatness have not included serving size in its assessment. It is not clear what effect this has on their findings and our study aimed to investigate this by comparing the relationships that days (serving size unaccounted for) and cans/day (serving size accounted for) of consumption have with ethnicity/country and fatness. METHODS: Daily nutrient intakes were calculated from a self-administered food frequency questionnaire from a cross-sectional health screening study. Participants were Pacific (n=954) and New Zealand European (n=1745) people aged 35 to 74 years. RESULTS: Compared to Australian youth, NZ Pacific youth consumed soft drinks more frequently but a larger difference was observed for cans/day. In a dose-dependent manner, FMI was positively associated with days (P=0.015) and cans/day (P=0.024) of consumption. However, cans/day showed a stronger relationship, with a standardised regression coefficient of 0.066, compared to 0.033 for days of consumption. CONCLUSIONS: It is useful to include serving size in the assessment of soft drink consumption. Excluding it leads to underestimation of both ethnic/country differences in daily volume of intake and associations with fatness.