Selective attrition and bias in a longitudinal health survey among survivors of a disaster

BACKGROUND: Little is known about the response mechanisms among survivors of disasters. We studied the selective attrition and possible bias in a longitudinal study among survivors of a fireworks disaster. METHODS: Survivors completed a questionnaire three weeks (wave 1), 18 months (wave 2) and four years post-disaster (wave 3). Demographic characteristics, disaster-related factors and health problems at wave 1 were compared between respondents and non-respondents at the follow-up surveys. Possible bias as a result of selective response was examined by comparing prevalence estimates resulting from multiple imputation and from complete case analysis. Analysis were stratified according to ethnic background (native Dutch and immigrant survivors). RESULTS: Among both native Dutch and immigrant survivors, female survivors and survivors in the age categories 25–44 and 45–64 years old were more likely to respond to the follow-up surveys. In general, disasters exposure did not differ between respondents and non-respondents at follow-up. Response at follow-up differed between native Dutch and non-western immigrant survivors. For example, native Dutch who responded only to wave 1 reported more depressive feelings at wave 1 (59.7%; 95% CI 51.2–68.2) than Dutch survivors who responded to all three waves (45.4%; 95% CI 41.6–49.2, p < 0.05). Immigrants who responded only to wave 1 had fewer health problems three weeks post-disaster such as depressive feelings (M = 69.3%; 95% CI 60.9–77.6) and intrusions and avoidance reactions (82.7%; 95% CI 75.8–89.5) than immigrants who responded to all three waves (respectively 89.9%; 95% CI 83.4–96.9 and 96.3%; 95% CI 92.3–100, p < .01). Among Dutch survivors, the imputed prevalence estimates of wave 3 health problems tended to be higher than the complete case estimates. The imputed prevalence estimates of wave 3 health problems among immigrants were either unaffected or somewhat lower than the complete case estimates. CONCLUSION: Our results indicate that despite selective response, the complete case prevalence estimates were only somewhat biased. Future studies, both among survivors of disasters and among the general population, should not only examine selective response, but should also investigate whether selective response has biased the complete case prevalence estimates of health problems by using statistical techniques such as multiple imputation

Autobiographical memory style in seasonal affective disorder and its relationship to future symptom remission

Autobiographical memory was examined in participants with seasonal affective disorder (SAD). In Experiment 1, participants with SAD performed an autobiographical memory task (AMT) in the winter, when depressed. The AMT required participants to generate autobiographical memories to positive and negative cue words. Symptom levels were reassessed in the summer, when participants were remitted. The number of overly general memories to positive cues generated when the SAD participants were depressed predicted symptom levels when remitted, over and above initial symptom levels, with greater winter overgenerality being associated with high levels of summer symptoms. However, this was dependent on the exact measure of depressive symptoms used. The degree of overgenerality of memories in SAD participants was further investigated in Experiment 2. Results revealed that SAD participants did not show elevated recall of overgeneral memories relative to controls. The results as a whole indicate that, even when levels of general memories are no greater in a given target group than in controls, the absolute level of general memories to positive cue words is still independently related to symptom outcome

Autobiographical memory style in seasonal affective disorder and its relationship to future symptom remission.

Autobiographical memory was examined in participants with seasonal affective disorder (SAD). In Experiment 1, participants with SAD performed an autobiographical memory task (AMT) in the winter, when depressed. The AMT required participants to generate autobiographical memories to positive and negative cue words. Symptom levels were reassessed in the summer, when participants were remitted. The number of overly general memories to positive cues generated when the SAD participants were depressed predicted symptom levels when remitted, over and above initial symptom levels, with greater winter overgenerality being associated with high levels of summer symptoms. However, this was dependent on the exact measure of depressive symptoms used. The degree of overgenerality of memories in SAD participants was further investigated in Experiment 2. Results revealed that SAD participants did not show elevated recall of overgeneral memories relative to controls. The results as a whole indicate that, even when levels of general memories are no greater in a given target group than in controls, the absolute level of general memories to positive cue words is still independently related to symptom outcome

Accumulation of Krebs cycle intermediaters and over-expression of HIF1alpha in tumours which result from germline FH and SDH mutations.

The nuclear-encoded Krebs cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDHB, -C and -D), act as tumour suppressors. Germline mutations in FH predispose individuals to leiomyomas and renal cell cancer (HLRCC), whereas mutations in SDH cause paragangliomas and phaeochromocytomas (HPGL). In this study, we have shown that FH-deficient cells and tumours accumulate fumarate and, to a lesser extent, succinate. SDH-deficient tumours principally accumulate succinate. In situ analyses showed that these tumours also have over-expression of hypoxia-inducible factor 1? (HIF1?), activation of HIF1? targets (such as vascular endothelial growth factor) and high microvessel density. We found no evidence of increased reactive oxygen species in our cells. Our data provide in vivo evidence to support the hypothesis that increased succinate and/or fumarate causes stabilization of HIF1? a plausible mechanism, inhibition of HIF prolyl hydroxylases, has previously been suggested by in vitro studies. The basic mechanism of tumorigenesis in HPGL and HLRCC is likely to be pseudo-hypoxic drive, just as it is in von Hippel–Lindau syndrome