Managing missing items in the Fagerström Test for Nicotine Dependence: a simulation study.

BACKGROUND: The Fagerström Test for Nicotine Dependence (FTND) is frequently used to assess the level of smokers' nicotine dependence; however, it is unclear how to manage missing items. The aim of this study was to investigate different methods for managing missing items in the FTND. METHODS: We performed a simulation study using data from the Arizona Smokers' Helpline. We randomly sampled with replacement from the complete data to simulate 1000 datasets for each parameter combination of sample size, proportion of missing data, and type of missing data (missing at random and missing not at random). Then for six methods for managing missing items on the FTND (two involving no imputation and four involving single imputation), we assessed the accuracy (via bias) and precision (via bias of standard error) of the total FTND score itself and of the regression coefficient for the total FTND score regressed on a covariate. RESULTS: When using the total FTND score as a descriptive statistic or in analysis for both types of missing data and for all levels of missing data, proration performed the best in terms of accuracy and precision. Proration's accuracy decreased with the amount of missing data; for example, at 9% missing data proration's maximum bias for the mean FTND was only - 0.3%, but at 35% missing data its maximum bias for the mean FTND increased to - 6%. CONCLUSIONS: For managing missing items on the FTND, we recommend proration, because it was found to be accurate and precise, and it is easy to implement. However, because proration becomes less accurate with more missing data, if more than ~ 10% of data are missing, we recommend performing a sensitivity analysis with a different method of managing missing data.

Correlates of cognitive impairment in adult cancer survivors who have received chemotherapy and report cognitive problems.

OBJECTIVE: Cognitive impairment negatively affects some cancer survivors who have completed chemotherapy; however, factors underlying this cognitive impairment remain poorly understood. We aimed to investigate (1) the relative importance of demographics, medical, and psychological characteristics associated with cognitive impairment and (2) the specific variables associated with cognitive impairment in adult cancer survivors who completed adjuvant chemotherapy. METHODS: We performed post hoc analyses of baseline data from early-stage cancer survivors with cognitive complaints who received adjuvant chemotherapy 0.5-5 years earlier and volunteered for a trial designed to improve cognition. The primary outcome of self-reported cognitive impairment was measured using a questionnaire; secondary outcome of objective cognitive impairment was measured using a computerized neuropsychological test battery. Hierarchical linear regression determined the relative importance of demographics, medical, and psychological characteristics in associations with both self-reported and objective cognitive impairment. RESULTS: The sample was 95% female and 89% breast cancer patients. The final model accounted for 33% of variation in self-reported cognitive impairment (n = 212, demographics 5%, medical 3%, and psychological 25%), with fatigue and stress as significant individual correlates (p values ≤ 0.0001). For the secondary analysis, the final model accounted for 19% of variation in objective cognitive impairment (n = 206, demographics 10%, medical 5%, and psychological 4%), with age, smoking history, and number of chemotherapy cycles as significant individual correlates. CONCLUSION: We found that psychological characteristics are more important than demographic and medical characteristics in self-reported cognitive impairment, whereas other characteristics are more important in objective cognitive impairment. This suggests clinicians should investigate possible psychological problems in cancer survivors who self-report cognitive impairment.

Excretion of polybrominated diphenyl ethers and AhR activation in breastmilk among firefighters.

Excretion of toxicants accumulated from firefighter exposures through breastmilk represents a potential hazard. We investigated if firefighting exposures could increase the concentration of polybrominated diphenyl ethers (PBDEs) and aryl hydrocarbon receptor (AhR) activation in excreted breastmilk. Firefighters and non-firefighters collected breastmilk samples prior to any firefighting responses (baseline) and at 2, 8, 24, 48, and 72 hours after a structural fire (firefighters only). Five PBDE analytes (BDEs 15, 28, 47, 99, and 153) detected in at least 90% of samples were summed for analyses. The AhR in vitro DR CALUX® bioassay assessed the mixture of dioxin-like compounds and toxicity from breastmilk extracts. Baseline PBDEs and AhR response were compared between firefighters and non-firefighters. Separate linear mixed models assessed changes in sum of PBDEs and AhR response among firefighters over time and effect modification by interior or exterior response was assessed. Baseline PBDE concentrations and AhR responses did not differ between the 21 firefighters and 10 non-firefighters. There were no significant changes in sum of PBDEs or AhR response among firefighters over time post-fire, and no variation by interior or exterior response. Plots of sum of PBDEs and AhR response over time demonstrated individual variation but no consistent pattern. Currently, our novel study results do not support forgoing breastfeeding after a fire exposure. However, given study limitations and the potential hazard of accumulated toxicants from firefighter exposures excreted via breastfeeding, future studies should consider additional contaminants and measures of toxicity by which firefighting may impact maternal and child health.