Handling missing data by re-approaching non-respondents

When handling missing data, a researcher should be aware of the mechanism underlying the missingness. In the presence of non-randomly missing data, a model of the missing data mechanism should be included in the analyses to prevent the analyses based on the data from becoming biased. Modeling the missing data mechanism, however, is a difficult task. One way in which knowledge about the missing data mechanism may be obtained is by collecting additional data from non-respondents. In this paper the method of re-approaching respondents who did not answer all questions of a questionnaire is described. New answers were obtained from a sample of these non-respondents and the reason(s) for skipping questions was (were) probed for. The additional data resulted in a larger sample and was used to investigate the differences between respondents and non-respondents, whereas probing for the causes of missingness resulted in more knowledge about the nature of the missing data patterns

The evaluation of the Center for Epidemiologic Studies Depression (CES-D) scale: depressed and positive affect in cancer patients and healthy reference subjects

This study examined the reliability and validity of a two-factor structure of the Center for Epidemiologic Studies Depression (CES-D) scale. The study was conducted in a large group of cancer patients (n = 475) and a matched reference group (n = 255). Both groups filled in a questionnaire at two points in time: patients 3 and 15 months after diagnosis. Factor analysis confirmed our hypothesis that the 16 negatively and four positively formulated items measure two relatively independent factors, i.e. Depressed Affect and Positive Affect. Therefore, these items should not be combined into an overall sumscore. In both groups, Depressed Affect proved to be a reliable and valid measure of depressive symptomatology, as indicated by its good internal consistency, its strong correlations with other measures of psychological distress and neuroticism, and its effectiveness in discriminating patients from the reference group on depressive symptomatology. In contrast, the validity of the Positive Affect factor could not be confirmed, since it was only weakly related to other measures of psychological distress and extraversion. Depressed and Positive Affect were about equally related to self-esteem, life satisfaction, and quality of life. These findings support the use of a sumscore based on the 16 negatively formulated CES-D items as a more valid measure of depressive symptomatology, in cancer patients and in healthy individuals from the general population

Predictors of non-pharmacological intervention in patients with paroxysmal atrial fibrillation:Value of neuroticism

Background: Non-pharmacological intervention is gaining increasing popularity in the treatment of patients with paroxysmal atrial fibrillation. We sought to investigate which factors play a role in the choice for non-pharmacological intervention with a particular focus on neuroticism. Methods: The study group comprised 73 patients with paroxysmal atrial fibrillation (mean age 55 13 years, 50 males). On average, patients had a 3-year-history of one symptomatic paroxysm per week lasting 2 It. The degree of neuroticism was assessed using the short scale Eysenck Personality Questionnaire. Results: During a mean follow-up period of 7.0 +/- 0.6 years, 20 patients (27%) underwent a non-pharmacological intervention for atria] fibrillation including His bundle ablation (n=1), maze operation (n=4), DDDR-pacemaker (n=10), pulmonary vein ablation (n=5). Multivariate regression analysis showed that age <55 years (odds ratio 5.3, 95% CI 1.1-24.5), frequency of paroxysms of atrial fibrillation > 1 per week (odds ratio 5.9, 95% CI 1.2-28.5) and total number of anti-arrhythmic drugs (class I and III) used > 2 (odds ratio 3.4, 95% CI 1.6-6.9) were predictive of non-pharmacological intervention (all p <0.05). In contrast, the degree of neuroticism was similar in patients who underwent non-pharmacological intervention as opposed to patients who did not undergo non-pharmacological intervention (4.5 +/- 3.3 vs. 4.0 +/- 2.9, p = NS). Conclusions: On the basis of this small study, neuroticism would not appear to play an important role in the decision to perform a nonpharmacological intervention. Instead, the data indicate that younger patients with pharmacologically refractory atrial fibrillation more often undergo non-pharmacological intervention. (c) 2005 Elsevier Ireland Ltd. All rights reserved