Currently, a growing number of programs become available in statistical software for multiple imputation of missing values. Among others, two algorithms are mainly implemented: Expectation Maximization (EM) and Multiple Imputation by Chained Equations (MICE). They have been shown to work well in large samples or when only small proportions of missing data are to be imputed. However, some researchers have begun to impute large proportions of missing data or to apply the method to small samples. A simulation was performed using MICE on datasets with 50, 100 or 200 cases and four or eleven variables. A varying proportion of data (3% -63%) was set as missing completely at random and subsequently substituted using multiple imputation by chained equations. In a logistic regression model, four coefficients, i.e. non-zero and zero main effects as well as non-zero and zero interaction effects were examined. Estimations of all main and interaction effects were unbiased. There was a considerable variance in the estimates, increasing with the proportion of missing data and decreasing with sample size. The imputation of missing data by chained equations is a useful tool for imputing small to moderate proportions of missing data. The method has its limits, however. In small samples, there are considerable random errors for all effects.

Background. Back pain is the most common form of pain and leads to high costs in all medical care systems. Objective. The present study examines the prevalence of back pain and its associations with some basic demographics. Methods. Two samples from Poland and Germany (about n = 500 each) were examined via Internet regarding back pain, gender, age, and body mass index (BMI). Results. Back pain is more common in women than in men (risk ratio about 1.7), and a high BMI constitutes an additional risk factor. Age was not related to back pain prevalence. Conclusion. Congruent results in two countries based on the same measure of back pain lead to the assumption that much of the variety found in estimates of back pain are due to inconsistent assessment. For future research, a definition of common criteria on how to assess back pain would be an asset.

ObjectiveVarious childhood adversities have been found to be associated with chronic pain in adulthood. However, associations were moderate in most studies, i.e. odds ratios (OR) were between one and two.MethodAn internet survey was performed in 508 Polish and 500 German subjects. A total of 19 childhood adversities were selected and their associations with headaches explored. Age, gender and country were included as potential confounders, as well as their two-way interaction with the risk factors.ResultsTwo strong risk factors were identified. (1) A combined score for physical and emotional neglect showed an odds ratio (OR) of 2.78 (p < .002) to the frequency of headache in adulthood as a main effect. (2) Father having had chronic pain showed an OR of 4.36 (p < .001) with headache in adulthood for women, but not for men (OR = 0.86, p < .556). The majority of the examined childhood adversities were not associated with adult headache, neither when tested individually nor as a sum score.ConclusionThis study confirms results from previous ones that childhood adversities may play a role in the development of adult headache, but it is a rather minor one. Contrary to other studies, neglect turned out to be one of the strongest predictors.

Background: Estimates about childhood abuse and neglect in various countries of the world indicate that cases of neglect outnumber cases of abuse by far. However, childhood neglect itself constitutes a neglected domain in psychological and medical research; far more articles have been published about abuse. Sampling and Methods: A ten-item questionnaire assessing childhood neglect was administered to two surveys in Poland (n = 508) and Germany (n = 500) via the internet. Results: Internal consistency was high in both countries, i.e. Cronbach's α was 0.82 in Poland and 0.88 in Germany. No distinction could be made between physical and emotional neglect. Values for neglect were similar for Polish and German men, but German women reported more neglect than Polish women. Conclusions: The Neglect Questionnaire is suitable for research in both Poland and Germany.