Rachel Huxley

Obesity and Risk of Colorectal Cancer: A Meta-analysis of 31 Studies with 70,000 Events

Background: Colorectal cancer is the second most common cause of death and illness in developed countries. Previous reviews have suggested that obesity may be associated with 30% to 60% greater risk of colorectal cancer, but little consideration was given to the possible effect of publication bias on the reported association. Methods: Relevant studies were identified through EMBASE and MEDLINE. Studies were included if they had published quantitative estimates of the association between general obesity [defined here as body mass index (BMI) ≥30 kg/m2] and central obesity (measured using waist circumference) and colorectal cancer. Random-effects meta-analyses were done, involving 70,000 cases of incident colorectal cancer from 31 studies, of which 23 were cohort studies and 8 were case-control studies. Results: After pooling and correcting for publication bias, the estimated relative risk of colorectal cancer was 1.19 [95% confidence interval (95% CI), 1.11-1.29], comparing obese (BMI ≥30 kg/m2) with normal weight (BMI <25 kg/m2) people; and 1.45 (95% CI, 1.31-1.61), comparing those with the highest, to the lowest, level of central obesity. After correcting for publication bias, the risk of colorectal cancer was 1.41 (95% CI, 1.30-1.54) in men compared with 1.08 (95% CI, 0.98-1.18) for women (Pheterogeneity <0.001). There was evidence of a dose-response relationship between BMI and colorectal cancer: for a 2 kg/m2 increase in BMI, the risk of colorectal cancer increased by 7% (4-10%). For a 2-cm increase in waist circumference, the risk increased by 4% (2-5%). Conclusions: Obesity has a direct and independent relationship with colorectal cancer, although the strength of the association with general obesity is smaller than previously reported. (Cancer Epidemiol Biomarkers Prev 2007;16(12):2533–47)

Systematic review: sodium bicarbonate treatment regimens for the prevention of contrast-induced nephropathy

In this review of 23 trials on whether sodium bicarbonate reduced risk for contrast-induced nephropathy (CIN) more than saline, the pooled relative risk for CIN was 0.62 (95% CI, 0.45 to 0.86). How...

The Burden of Overweight and Obesity in the Asia-Pacific Region

The rise in the prevalence of overweight and obesity (body mass indexu2003≥25u2003kgu2003m−2) is, in part, a negative consequence of the increasing economic developments of many lower‐ and middle‐income countries in the Asia–Pacific region. To date, there has been no systematic quantification of the scale of the problem in countries of this region. From the most recent nationally representative estimates for the prevalence of overweight and obesity in 14 countries of the region, it is apparent that overweight and obesity is endemic in much of the region, prevalence ranging from less than 5% in India to 60% in Australia. Moreover, although the prevalence in China is a third of that in Australia, the increase in prevalence in China over the last 20u2003years was 400% compared with 20% in Australia. In addition, across various countries in the region, the population attributable fractions because of overweight and obesity ranged from 0.8% to 9.2% for coronary heart disease mortality, 0.2% to 2.9% for haemorrhagic stroke mortality, and 0.9% to 10.2% for ischaemic stroke mortality. These results indicate that consequences of overweight and obesity for health and the economy of many of these countries are likely to increase in coming years.

Type 2 Diabetes as a Risk Factor for Dementia in Women Compared With Men: A Pooled Analysis of 2.3 Million People Comprising More Than 100,000 Cases of Dementia

OBJECTIVE Type 2 diabetes confers a greater excess risk of cardiovascular disease in women than in men. Diabetes is also a risk factor for dementia, but whether the association is similar in women and men remains unknown. We performed a meta-analysis of unpublished data to estimate the sex-specific relationship between women and men with diabetes with incident dementia. RESEARCH DESIGN AND METHODS A systematic search identified studies published prior to November 2014 that had reported on the prospective association between diabetes and dementia. Study authors contributed unpublished sex-specific relative risks (RRs) and 95% CIs on the association between diabetes and all dementia and its subtypes. Sex-specific RRs and the women-to-men ratio of RRs (RRRs) were pooled using random-effects meta-analyses. RESULTS Study-level data from 14 studies, 2,310,330 individuals, and 102,174 dementia case patients were included. In multiple-adjusted analyses, diabetes was associated with a 60% increased risk of any dementia in both sexes (women: pooled RR 1.62 [95% CI 1.45–1.80]; men: pooled RR 1.58 [95% CI 1.38–1.81]). The diabetes-associated RRs for vascular dementia were 2.34 (95% CI 1.86–2.94) in women and 1.73 (95% CI 1.61–1.85) in men, and for nonvascular dementia, the RRs were 1.53 (95% CI 1.35–1.73) in women and 1.49 (95% CI 1.31–1.69) in men. Overall, women with diabetes had a 19% greater risk for the development of vascular dementia than men (multiple-adjusted RRR 1.19 [95% CI 1.08–1.30]; P < 0.001). CONCLUSIONS Individuals with type 2 diabetes are at ∼60% greater risk for the development of dementia compared with those without diabetes. For vascular dementia, but not for nonvascular dementia, the additional risk is greater in women.

Cigarette Smoking, Systolic Blood Pressure, and Cardiovascular Diseases in the Asia-Pacific Region

Background and Purpose— Smoking and increased levels of blood pressure (BP) substantially increase the risk of cardiovascular diseases (CVD). If these 2 risk factors have a synergistic impact on cardiovascular events, lowering BP and quitting smoking will contribute more to reducing CVD than would be expected from ignoring their interaction. Methods— Individual participant data were combined from 41 cohorts, involving 563 144 participants (82% Asian). During a median of 6.8 years follow-up, 4344 coronary heart disease (CHD) and 5906 stroke events were recorded. Repeat measures of systolic blood pressure (SBP) were used to adjust for regression dilution bias. Hazard ratios (HRs) and 95% confidence intervals (CIs) for SBP by cigarette smoking status were estimated from Cox proportional hazard models adjusted for age and stratified by study and sex. Results— Data suggested a log-linear relationship between SBP and all subtypes of CVD. The HRs relating SBP to both CHD and ischemic stroke were broadly similar irrespective of smoking status (P≥0.1). For hemorrhagic stroke (intracerebral hemorrhage), the HRs (95% CIs) for an additional 10 mm Hg increment in SBP were 1.81 (1.73 to 1.90) for present smokers and 1.66 (1.59 to 1.73) for nonsmokers (P=0.003). For every subtype of cardiovascular events, similar results were found for analyses involving only fatal events. Conclusions— Smoking exacerbated the impact of SBP on the risk of hemorrhagic stroke. Although quitting smoking and lowering BP are both crucial for prevention of CVD, combining the 2 could be expected to have extra beneficial effect on preventing hemorrhagic stroke.

The Effect of Modifiable Risk Factors on Pancreatic Cancer Mortality in Populations of the Asia-Pacific Region

Background: Pancreatic cancer accounts for about 220,000 deaths each year. Known risk factors are smoking and type 2 diabetes. It remains to be seen whether these risk factors are equally important in Asia and whether other modifiable risk factors have important associations with pancreatic cancer. Methods: An individual participant data analysis of 30 cohort studies was carried out, involving 420,310 Asian participants (33% female) and 99,333 from Australia/New Zealand (45% female). Cox proportional hazard models, stratified by study and sex and adjusted for age, were used to quantify risk factors for death from pancreatic cancer. Results: During 3,558,733 person-years of follow-up, there were 324 deaths from pancreatic cancer (54% Asia and 33% female). Mortality rates (per 100,000 person-years) from pancreatic cancer were 10 for men and 8 for women. The following are age-adjusted hazard ratios (95% confidence interval) for death from pancreatic cancer: for current smoking, 1.61 (1.12-2.32); for diabetes, 1.76 (1.15-2.69); for a 2-cm increase in waist circumference, 1.08 (1.02-1.14). All three relationships remained significant (P < 0.05) after adjustment for other risk factors. There was no evidence of heterogeneity in the strength of these associations between either cohorts from Asia and Australia/New Zealand or between the sexes. In men, the combination of cigarette smoking and diabetes more than doubled the likelihood of pancreatic cancer (2.47; 95% confidence interval, 1.17-5.21) in both regions. Conclusions: Smoking, obesity, and diabetes are important and are potentially modifiable risk factors for pancreatic cancer in populations of the Asia-Pacific region. Activities to prevent them can be expected to lead to a major reduction in the number of deaths from this cancer, particularly in Asia with its enormous population. (Cancer Epidemiol Biomarkers Prev 2006;15(12):2435–40)

The association between lung cancer incidence and ambient air pollution in China: A spatiotemporal analysis.

BACKGROUNDnChina is experiencing more and more days of serious air pollution recently, and has the highest lung cancer burden in the world.nnnOBJECTIVESnTo examine the associations between lung cancer incidence and fine particles (PM2.5) and ozone in China.nnnMETHODSnWe used 75 communities data of lung cancer incidence from the National Cancer Registration of China from 1990 to 2009. The annual concentrations of fine particles (PM2.5) and ozone at 0.1°×0.1° spatial resolution were generated by combing remote sensing, global chemical transport models, and improvements in coverage of surface measurements. A spatial age-period-cohort model was used to examine the relative risks of lung cancer incidence associated with the air pollutants, after adjusting for impacts of age, period, and birth cohort, sex, and community type (rural and urban) as well as the spatial variation on lung cancer incidence.nnnRESULTSnThe relative risks of lung cancer incidence related to a 10 µg/m(3) increase in 2-year average PM2.5 were 1.055 (95% confidence interval (CI): 1.038, 1.072) for men, 1.149 (1.120, 1.178) for women, 1.060 (1.044, 1.075) for an urban communities, 1.037 (0.998, 1.078) for a rural population, 1.074 (1.052, 1.096) for people aged 30-65 years, and 1.111 (1.077, 1.146) for those aged over 75 years. Ozone also had a significant association with lung cancer incidence.nnnCONCLUSIONSnThe increased risks of lung cancer incidence were associated with PM2.5 and ozone air pollution. Control measures to reduce air pollution would likely lower the future incidence of lung cancer.

Blood pressure variables and cardiovascular risk: new findings from ADVANCE

The relative importance of various blood pressure indices on cardiovascular risk in people with type 2 diabetes mellitus has not been established. This study compares the strengths of the associations between different baseline blood pressure variables (systolic blood pressure [SBP], diastolic blood pressure [DBP], pulse pressure [PP], and mean arterial pressure) and the 4.3-year risk of major cardiovascular events in the Action in Diabetes and Vascular Disease: Preterax and Diamicron-Modified Release Controlled Evaluation Study. Mean (SD) age for the 11 140 participants was 65.8 years (6.4 years). During follow-up, 1000 major cardiovascular events, 559 major coronary events, and 468 cardiovascular deaths were recorded. After adjustment for age, sex, and treatment allocation, the hazard ratios (95% CIs) associated with 1 increment in SD for the risk of major cardiovascular events were 1.17 (1.10 to 1.24) for SBP; 1.20 (1.13 to 1.28) for PP; 1.12 (1.05 to 1.19) for mean arterial pressure; and 1.04 (0.98 to 1.11) for DBP. The areas under the receiver operating characteristic curve were slightly higher for SBP and PP compared with mean arterial pressure and DBP for major cardiovascular and coronary events. Using achieved instead of baseline blood pressure values marginally improved the effect estimates for SBP, DBP, and mean arterial pressure, with no significant differences in the areas under the receiver operating characteristic curve between models with SBP and those with PP. In conclusion, SBP and PP are the 2 best and DBP is the least effective determinant of the risk of major cardiovascular outcomes in the relatively old patients with type 2 diabetes mellitus participating in the Action in Diabetes and Vascular Disease: Preterax and Diamicron-Modified Release Controlled Evaluation Study. However, SBP may be the simplest and most useful predictor across a wider range of age groups and populations.

Is central obesity a better discriminator of the risk of hypertension than body mass index in ethnically diverse populations

Objective To compare the performance of body mass index (BMI) against waist circumference, waist: hip ratio (WHR) and waist: height ratio in the discrimination of hypertension in ethnically diverse populations. Methods Meta-analysis of 19 cross-sectional studies. Main outcome measures Discrimination of hypertension (SBP/DBP ≥ 140/90 mmHg) was adjudicated from Receiver Operating Characteristic curves; optimum thresholds were defined as those that maximized sensitivity plus specificity. Results Irrespective of which measure of overweight was used, the strength of the association with blood pressure was consistently greater among Asians compared with Caucasians or Pacific Islanders; however, in all regions, and for all anthropometric measures, the increment in blood pressure, and the additional risk of hypertension, were broadly similar for the same relative increment in each of the four measures. Optimum thresholds varied by region; WHR was the most consistent between the regions, with thresholds of 0.92–0.94 for men and 0.80–0.88 for women. No anthropometric variable was systematically better than others at the discrimination of hypertension. Conclusions Blood pressure is similarly associated with each of the four measures of overweight chosen, but the associations were stronger among Asians. WHR has advantages in terms of consistency of thresholds for hypertension across ethnic groups in the Asia–Pacific.

The hazards and benefits associated with smoking and smoking cessation in Asia: a meta-analysis of prospective studies

Objective: To provide the most reliable evidence as to the nature of the associations between smoking and cause-specific illness, as well as the expected benefits from quitting smoking, in studies conducted in Asia, where smoking remains popular among men. Data sources: Studies published between January 1966 and October 2008, identified in the Medline search strategy with medical subject headings, in addition to studies from the Asia Pacific Cohort Studies Collaboration. Study selection: Studies were considered to be relevant if they were prospective studies, in an Asian setting that reported on the association between smoking, quitting and cause-specific illness. Data extraction: Two reviewers independently screened all identified articles for possible inclusion and extracted data. Data synthesis: The pooled relative risks (RRs) for incidence or mortality, comparing current to never smokers were always significantly higher than unity; the highest was for lung cancer: 3.54 (95% confidence interval 3.00 to 4.17). The pooled RRs for former smokers (compared to never smokers) were also always significantly higher than unity, and were lower than in current smokers, for coronary heart disease, stroke, lung and upper aero-digestive tract cancer. Only for respiratory disease was the RR for former smokers higher than that for current smokers. Conclusions: This meta-analysis has shown that, despite the relative immaturity of the smoking epidemic in Asia, smoking is unquestionably a major contributor to ill health and death. However, the beneficial effects of quitting are not yet always apparent, most probably because quitting is a consequence of ill health and the relative unpopularity of smoking cessation in many Asian populations.