Association between dietary inflammatory index and serum C-reactive protein concentrations in the Japan Collaborative Cohort Study

Diet plays an important role in the regulation of chronic inflammation, which is linked to cardiovascular disease (CVD) and several cancers. The dietary inflammatory index (DII^®) was developed to estimate the inflammatory potential of an individual’s diet. We examined the association between DII scores and serum high-sensitivity C-reactive protein (hs-CRP) concentrations using the baseline data from the Japan Collaborative Cohort Study (JACC Study). Data were from 1176 control subjects (650 men and 526 women) in a nested case-control study of several cancers and CVD in the JACC Study who were free of cancer and CVD at baseline. DII scores were calculated from 26 food parameters that were derived from a validated food frequency questionnaire administered at the baseline. Energy-adjusted DII scores were calculated using the residual method. Serum hs-CRP concentrations were measured by latex-enhanced nephelometry or enzyme-immunoassay. In multivariable logistic regression analysis adjusting for potential confounders including sex, age, smoking habits, drinking habits, body mass index, and history of hypertension, the odds ratio (OR) and 95% confidence intervals (CI) for high serum hs-CRP concentrations (>1.0 mg/L) was significantly higher in the highest versus the lowest DII quartile (OR_Quartile4vs1 = 1.32, 95% CI = 1.01 to 2.52). Likewise, a 1-point increase in DII score was associated with a 14% increased risk of high serum hs-CRP concentrations (OR_Continuous = 1.09, 95%CI = 1.01 to 1.19). A pro-inflammatory diet, as represented by high DII scores, was associated with high serum hs-CRP concentrations in this Japanese population.

Serum High-Sensitivity C-Reactive Protein Levels and the Risk of Atrial Fibrillation in Japanese Population: the Circulatory Risk in Communities Study

AIM

This study aimed to investigate the association between the serum high-sensitivity C-reactive protein (hs-CRP) levels and incident atrial fibrillation risk in the general Japanese population, who have lower hs-CRP levels than the Western population, and assess whether the association is modified by sex, overweight, hypertension, and smoking status.

METHODS

We conducted a prospective study in 6517 Japanese men and women aged 40-79 years without atrial fibrillation at baseline and enrolled in the Circulatory Risk in Communities Study (2002-2008). The hs-CRP levels were measured using the latex particle-enhanced immunonephelometric assay. Atrial fibrillation was identified using standard 12-lead electrocardiograms and information on physician-diagnosed atrial fibrillation history from the follow-up surveys. We used a Cox proportional hazard regression stratified by community.

RESULTS

During a median follow-up of 11 years, 127 new cases of atrial fibrillation (74 and 53 cases among men and women, respectively) were found. Compared to the lowest quintile of hs-CRP levels, the multivariable hazard ratios (95% confidence intervals) were 2.54 (1.17-5.50), 2.28 (1.06-4.93), 2.92 (1.37-6.23), and 2.77 (1.30-5.91) for the second, third, fourth, and fifth (highest) quintiles, respectively. There was no significant effect modification by sex, overweight, hypertension, and smoking status (P for interaction ＞0.05).

CONCLUSIONS

Elevated hs-CRP levels were significantly associated with increased risk of atrial fibrillation in the Japanese population. The association of hs-CRP levels with incident atrial fibrillation did not vary according to sex, overweight, hypertension status, or smoking status.

Ten-year standardization of lipids and high-sensitivity C-reactive protein in a randomized controlled trial to assess the effects of statins on secondary stroke prevention: Japan Statin Treatment Against Recurrent Stroke

Background The Japan Statin Treatment Against Recurrent Stroke (J-STARS) is a clinical trial that administered pravastatin for secondary stroke prevention. Lipid concentrations are a well-established risk factor for cerebrovascular diseases. Elevated high-sensitivity C-reactive protein (hs-CRP) indicates a high risk of inflammatory reactions. In clinical trials, internationally approved standardization is essential for obtaining study results that are comparable with those from overseas. Therefore, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG) and hs-CRP were standardized throughout a 10-year study period. Methods J-STARS specified a single clinical laboratory for blood analyses. Four lipids were evaluated by calculating the total error: accuracy (absolute mean %bias vs. reference value) + precision (1.96 among-run coefficient of variation [CV, %]). Accuracy for hs-CRP was ensured using a calibrator traceable to the international plasma protein reference material and precision was evaluated by CV. Results Average total errors (standard deviation, %) throughout the study period were as follows: TC 1.35% (0.290%), HDL-C 2.45% (1.087%), LDL-C 2.65% (0.956%) and TG 3.70% (0.559%). Four lipids met the performance criteria of the US Centers for Disease Control and Prevention (CDC). The precision of hs-CRP was 3.28% (0.627%), which met the performance criterion established by the American Heart Association/CDC. Conclusions Based on standardization, the results of J-STARS appear to be comparable with those of similar intervention-based clinical studies on statins overseas. These study results will contribute to the establishment of preventive measures against recurrent stroke in Japanese patients. J-STARS is registered in ClinicalTrials.gov under NCT00221104.

Nomograms incorporating serum C-reactive protein effectively predict mortality before and after surgical treatment of renal cell carcinoma

OBJECTIVES

To incorporate C-reactive protein into nomograms estimating survival in patients with renal cell carcinoma.

METHODS

Patients undergoing surgery for renal cell carcinoma from 2005-2012 were studied retrospectively. Multivariable Cox proportional hazards regression and competing risks regression models including stage, grade, C-reactive protein levels and presence of metastatic disease were constructed. Outcomes analyzed include overall mortality overall mortality and renal cell carcinoma-specific mortality.

RESULTS

The cohort included 516 patients with a mean follow up of 1.7 years (SD 1.4 years). One- and 3-year renal cell carcinoma-specific mortality was 8.8% and 13.5%, respectively. Four nomograms were generated using overall mortality and renal cell carcinoma-specific mortality as end-points, two each for pre- and postoperative counseling. The factor with the largest effect on all nomograms was preoperative C-reactive protein. Based on the internal validation with bootstrapping, the concordance indices for renal cell carcinoma-specific mortality in the preoperative nomogram, postoperative nomogram, and the Mayo Clinic stage, size, grade and necrosis score were 0.889, 0.893, and 0.832, respectively (P = 0.005 and 0.002 comparing with stage, size, grade and necrosis scores for preoperative or postoperative nomograms). For overall mortality, the preoperative nomogram, postoperative nomogram, and stage, size, grade and necrosis score showed concordance indices of 0.866, 0.897, and 0.828, respectively (P = 0.123 and 0.008 compared with stage, size, grade and necrosis score for preoperative or postoperative nomograms).

CONCLUSIONS

We have generated nomograms incorporating serum C-reactive protein levels that effectively predict overall mortality and renal cell carcinoma specific mortality. Our findings warrant external validation.

Measurement performance of reagent manufacturers by Centers for Disease Control and Prevention/Cholesterol Reference Method Laboratory Network lipid standardization specified for metabolic syndrome-focused health checkups program in Japan

AIM

This study was designed to clarify the current measurement performance of 7 reagent manufacturers for high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC) and triglycerides (TG) specified for the metabolic syndrome (MetS)-focused health checkups program in Japan.

METHODS

Twenty HDLC, 21 LDLC and 9 TG analytical reagent/instrument/calibrator systems (system), and combinations of reagent lots, instrument models and calibrator lots, underwent Centers for Disease Control and Prevention (CDC)/Cholesterol Reference Method Laboratory Network (CRMLN) lipid standardization. Eighty and 100% systems were requested to achieve an accuracy of within +/-1% and +/-2% of the reference value, so that a clinical laboratory can meet the CDC criteria.

RESULTS

The CDC performance criteria of HDLC, LDLC and TG require an accuracy of within +/-5%, +/-4% and +/-5%, respectively. For HDLC, all 20 systems met the criteria. Fourteen (70.0%) and 18 (90.0%) systems were within +/-1% and +/-2%, respectively. For LDLC, 14 (66.7%) of 21 systems met the criteria, but 7 (33.3%) failed. Five (23.8%) and 17 (81.0%) systems were within +/-1% and +/-2%, respectively. For TG, 8 of 9 systems met the criteria. Two (22.2%) and 4 (44.4%) systems were within +/-1% and +/-2%, respectively. The minimum and maximum differences of a specified sample among manufacturers were 1.6 and 11.0 mg/dL for HDLC, 7.8 and 33.0 mg/dL for LDLC, and 2.8 and 27.4 mg/dL for TG, respectively.

CONCLUSION

Homogeneous HDLC methods are acceptable for MetS, but further accuracy improvement of homogeneous LDLC and TG methods will be needed because of their poor performance.

C-reactive protein levels and risk of mortality from cardiovascular disease in Japanese: the JACC Study

OBJECTS

Limited evidence of association between C-reactive protein levels and cardiovascular disease has been produced for Japanese whose median protein levels are low by western standards.

METHODS

We conducted a nested case-control study as part of the Japan Collaborative Cohort Study for evaluation of cancer risk (JACC Study). A total of 39,242 subjects 40-79 years of age provided serum samples at baseline between 1988 and 1990. During the 13-year follow-up, there were 525 deaths from total strokes (ICD10: I60-I69), 209 coronary heart diseases (I20-I25) and 939 total cardiovascular diseases (I00-I99). The control subjects were matched for sex, age, area of residence and year of serum storage, and analyses were conducted after further adjustment for cardiovascular risk factors. Serum high-sensitivity C-reactive protein (hs-CRP) levels were measured with ultra-sensitive latex-enhanced immunoassay.

RESULTS

Median hs-CRP levels for controls were 0.40 mg/L for men and 0.41 mg/L for women. Hs-CRP levels were positively associated with risks of mortality from stroke, coronary heart disease, and total cardiovascular disease for men. The respective multivariable odds ratios (OR 95% CI) for the highest (>or=0.85 mg/L) vs. lowest (<0.19 mg/L) quartiles of hs-CRP for men were 1.60 (0.90-2.85), 3.68 (1.02-13.3), and 2.31 (1.49-3.59). For women, positive associations with hs-CRP levels were weaker, reaching statistical significance only for total cardiovascular disease: OR=1.69 (1.06-2.68). The positive association with total cardiovascular disease did not vary according to sex, age, smoking status, or body mass index.

CONCLUSIONS

Higher serum hs-CRP levels were associated with higher mortality from cardiovascular disease in Japanese.

Inflammation as a cardiovascular risk factor and pulse wave velocity as a marker of early-stage atherosclerosis in the Japanese population

Inflammation and pulse wave velocity (PWV) are a potential risk factor and marker, respectively, for atherosclerosis in the primary prevention setting. Atherosclerosis is now generally accepted to be an inflammatory disorder of the arterial wall, and the high-sensitivity C-reactive protein (hs-CRP) level has been reported to be a strong predictor of cardiovascular events. High-sensitivity-CRP is associated with two factors related to inflammation: (1) the local production of CRP by atheromatous tissue or coronary artery smooth muscle cells and (2) adipose tissue as a potent source of inflammatory cytokines. Based on studies in North America and Europe, hs-CRP has been established as a cardiovascular risk factor and a cut-off value has been recommended. However, Japanese have lower hs-CRP values than their Western counterparts, partly because Japanese have a lower body mass index (BMI), which correlates positively to hs-CRP, and partly because lifestyle and genetic factors can affect hs-CRP values. Therefore, a cut-off value needs to be established by cohort studies for the Japanese population. Carotid-femoral PWV is most commonly measured by applanation tonometry, particularly in Europe, but this method is critically dependent upon the accurate placing of transducers over the arteries and is both time-consuming and complex. A novel device has been recently developed in Japan that measures brachial-ankle PWV (baPWV) using a volume-rendering method. Brachian-ankle PWV is a suitable screening method because of its technical simplicity and shorter measurement time. It is associated not only with conventional cardiovascular risk factors but also with new risk factors, such as inflammation, gamma-glutamyltransferase, chronic kidney disease, and psychosocial factors. However, a suitable cut-off value has yet to be established.

Establishment of long-term monitoring system for blood chemistry data by the national health and nutrition survey in Japan

AIM

We established a monitoring system for the annual follow-up of blood chemistry data obtained by the National Health and Nutrition Survey in Japan.

METHODS

Blood chemistry testing has been entrusted to SRL Inc. We used two external quality control assurance programs established by the Japan Medical Association (JMA) and by CDC/CRMLN during the previous 8-year period. Ten analytes were measured: total cholesterol, HDL cholesterol, triglycerides, urea nitrogen, uric acid, creatinine, AST (GOT), ALT (GPT), gamma-GT (gamma-GTP), and glucose. Total error (TE) was calculated from accuracy by the JMA program and precision by internal quality control of SRL. The permissible range of TE values was determined to be 50% of the evaluation limit on one side in the evaluation criteria of the College of American Pathologists (CAP). When TE fell within the permissible range, the follow-up of annual changes was considered possible.

RESULTS

Annual follow-up of blood chemistry data was considered possible for all the analytes except urea nitrogen. Based on this study, new permissible TE ranges are proposed.

CONCLUSION

We confirmed the functioning of the monitoring system for the annual follow-up of blood chemistry data obtained by the National Health and Nutrition Survey in Japan.