Urbanicity, posttraumatic stress disorder, and effect modification by socioeconomic position: A nested case-control study of the Korean National Health Insurance Database.

BACKGROUND: We aimed to estimate the association between urbanicity and the onset of posttraumatic stress disorder (PTSD) and to investigate heterogeneity therein according to age and socioeconomic position (SEP). METHODS: We analyzed administrative data from the Korean National Health Insurance Database for patients with PTSD from 2004 to 2018 (N = 109,230) and for a 1:4 sample of age-, sex-, and enrollment year-matched controls. Information on eligibility, SEP (proxied by insurance premium), place of residence, diagnosis, and medical claims was obtained. Urbanicity of administrative districts was assessed using data from the Korean Statistical Information Service, 2005-2018. We estimated hazard ratios (HRs) from baseline and time-dependent models. Subgroup analyses and polynomial splines were used to investigate heterogeneity by age and SEP. RESULTS: Urbanicity was associated with an increased risk of PTSD (per 10%p increase, HR = 1.056, 95% CI 1.050-1.061). A positive association was estimated among patients aged 0-29 years (HR = 1.115, CI 1.106-1.124), while negative associations were estimated among patients aged 30-64 years (HR = 0.990, CI 0.987-0.994) and 65 years or older (HR = 0.992, CI 0.979-1.014). The estimated associations with urbanicity were more prominent at the extremes of SEP, but only among younger participants. CONCLUSION: Urban residence was associated with an increased risk of PTSD diagnosis. The estimated association was larger among younger individuals (but not among middle-aged and older individuals). Among younger individuals, the estimated association was larger at both extremes of SEP.

Effect of chemotherapy and radiotherapy on cognitive impairment in colorectal cancer: evidence from Korean National Health Insurance Database Cohort.

OBJECTIVES: We investigated the risk of chemotherapy-related and radiotherapy-related cognitive impairment in colorectal cancer patients. METHODS: Medical use data of colorectal cancer patients were obtained from the Korean National Health Insurance Database from 2004 to 2018. We randomly selected 40% of all colorectal cancer patients (n=148,848). Cognitive impairment was defined as having 1 or more International Classification of Diseases, 10th revision diagnostic codes for dementia or mild cognitive impairment. Patients aged 18 years or younger, patients diagnosed with cognitive impairment before colorectal cancer diagnosis (n=8,225), and patients who did not receive primary resection (n=45,320) were excluded. The effects of individual chemotherapy regimens on cognitive impairment were estimated. We additionally estimated the effect of radiotherapy in rectal cancer patients. Time-dependent competing risk Cox regression was conducted to estimate the overall and age-specific hazard ratios (HR) separately for colon and rectal cancer. Landmark analyses with different lag times were conducted as sensitivity analyses. RESULTS: Chemotherapy did not increase the risk of cognitive impairment in colorectal cancer patients (colon cancer: HR, 0.92; 95% confidence interval [CI], 0.83 to 1.03; rectal cancer: HR, 0.88; 95% CI, 0.75 to 1.04), while radiotherapy was negatively associated with cognitive impairment in rectal cancer patients (HR, 0.01; 95% CI, 0.84 to 0.99). Varying directions of the associations between regimens and cognitive impairment were detected. The adverse effect of certain chemotherapy regimens on cognition was more prominent in older adults. CONCLUSIONS: Chemotherapy and radiotherapy did not increase the risk of cognitive impairment. Older patients with low cognitive reserve could be affected by the adverse cognitive effects of chemotherapy.

Consumption of Fish and ω-3 Fatty Acids and Cancer Risk: An Umbrella Review of Meta-Analyses of Observational Studies.

Multiple studies have suggested that ω-3 fatty acid intake may have a protective effect on cancer risk; however, its true association with cancer risk remains controversial. We performed an umbrella review of meta-analyses to summarize and evaluate the evidence for the association between ω-3 fatty acid intake and cancer outcomes. We searched PubMed, Embase, and the Cochrane Database of Systematic Reviews from inception to December 1, 2018. We included meta-analyses of observational studies that examined associations between intake of fish or ω-3 fatty acid and cancer risk (gastrointestinal, liver, breast, gynecologic, prostate, brain, lung, and skin) and determined the level of evidence of associations. In addition, we appraised the quality of the evidence of significant meta-analyses by using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. We initially screened 598 articles, and 15 articles, including 57 meta-analyses, were eligible. Among 57 meta-analyses, 15 reported statistically significant results. We found that 12 meta-analyses showed weak evidence of an association between ω-3 fatty acid intake and risk of the following types of cancer: liver cancer (n = 4 of 6), breast cancer (n = 3 of 14), prostate cancer (n = 3 of 11), and brain tumor (n = 2 of 2). In the other 3 meta-analyses, studies of endometrial cancer and skin cancer, there were no assessable data for determining the evidence levels. No meta-analysis showed convincing, highly suggestive, or suggestive evidence of an association. In the sensitivity analysis of meta-analyses by study design, we found weak associations between ω-3 fatty acid intake and breast cancer risk in cohort studies, but no statistically significant association in case-control studies. However, the opposite results were found in case of brain tumor risk. Although ω-3 fatty acids have been studied in several meta-analyses with regard to a wide range of cancer outcomes, only weak associations were identified in some cancer types, with several limitations. Considering the nonsignificant or weak evidence level, clinicians and researchers should cautiously interpret reported associations between ω-3 fatty acid consumption and cancer risks.

Association between sedative-hypnotic medication use and incidence of cancer in Korean Nation Health Insurance Service data.

OBJECTIVES: We aimed to investigate the association between the use of various sedative-hypnotics and the incidence of overall and individual cancers in a large, population-based, retrospective cohort study. METHODS: We selected a 5% random sample of individuals aged 50 years or older from data maintained by the Korean National Health Insurance Service for the years 2002-2015, excluding individuals with a prior diagnosis of cancer and with any sedative-hypnotic use in the initial two years of follow-up, leaving 236,759 participants for the final analysis. Exposure to sedative-hypnotics was defined by type of drug, standardized to a defined daily dose, and coded as a time-varying variable. Cox proportional hazard models were applied after adjusting for sex, socio-economic status, and comorbidities. RESULTS: We observed increased risk for overall cancer among men and women who used sedative-hypnotics (hazard ratio (HR) = 1.07, 95% confidence interval (CI) = 1.01-1.13 for men; HR = 1.21, 95% CI = 1.09-1.25 for women) compared with non-users after full adjustment. In the fully adjusted model, women with any sedative-hypnotic use had significantly increased risk for thyroid (HR = 1.53, 95% CI = 1.24-1.87), breast (HR = 1.29, 95% CI = 1.04-1.61), ovarian (HR = 1.65, 95% CI = 1.10-2.46), and lung cancer (HR = 1.40, 95% CI = 1.17-1.69) compared with non-users. Men with sedative-hypnotic use had increased risk for prostate (HR = 1.36, 95% CI = 1.16-1.58), brain (HR = 1.67, 95% CI = 1.04-2.69), and lung cancer (HR = 1.20, 95% CI = 1.07-1.35) compared with non-users. CONCLUSION: We found a significant increase in overall cancer incidence among participants who used sedative-hypnotics, and both male and female sedative-hypnotic users had significantly increased risk for certain types of cancer.