Interaction Of Hypertension And Different Obesity Indexes On Kidney Damage:A Survey From A Rural Population In Northeast China

Objective:Kidney disease is a worldwide public health problem,its prevention and control will significantly improve the health level of the population.In addition,kidney disease,in addition to causing direct health hazards,is also associated with a variety of cardiovascular diseases and has a mutually reinforcing effect.Most previous studies have explored the independent effect of a single risk factor on the occurrence of kidney damage,or explored the combined effect of more than three risk factors on kidney damage in metabolic syndrome,but few have proven whether there will be synergistic interaction between the two variable risk factors to further increase the risk of kidney damage in patients.In summary,the purpose of this study was to explore whether there is an interaction between hypertension and different obesity indicators that puts patients at greater risk for kidney damage than the sum or sum of their individual effects.Methods:This study analyzed data from 9,198 participants in the cardio-cerebrovascular Health Study in rural Northeast China from 2015 to 2016.Patients were divided into gender groups with and without renal impairment according to whether the eGFR was less than 60mL/（min·1.73m²）.The baseline features were compared between the two groups.Logistic regression analysis model was used to analyze the strength of association between obesity and hypertension and the risk of kidney damage,and the interaction between additive model and multiplicative model was analyzed.Additive interactions were calculated by the relative excess risk due to interaction（RERI）,attributable proportion due to interaction（AP）and Synergy index（S）.The relative excess risk due to interaction was calculated as RERI=OR₁₁-(OR₁₀+OR₀₁)+1,OR₁₁referred to the OR value when hypertension and obesity coexisted,OR₁₀represented the OR value when only hypertension existed,OR₀₁referred to when only obesity existed.AP was defined as RERI/OR₁₁,which reflected the relative proportion of the risk caused by the interaction to the total risk.S=(OR₁₁–1)/[(OR₁₀-1)+(OR₀₁-1)].General obesity was defined as body mass index（BMI）≥28kg/m².Central obesity had the following three different definitions:（1）male:waist circumference（WC）≥90 cm,female:WC≥80 cm;（2）waist-to-height ratio（WHt R）≥0.5;（3）male:waist to hip ratio（WHpR）≥0.9,female:WHpR≥0.85.Results:A total of 9198 subjects were included in this study,and the prevalence of renal impairment was 2.49%（229 cases）.After controlling for potential confounding factors,the risk of kidney damage（OR,95%CI）in the general population was 3.913（2.505,6.112）times higher in participants with both hypertension and general obesity than in the control group with normal blood pressure and normal weight.The risk of kidney damage was 4.814（2.813,8.238）,5.187（2.523,10.663）and 6.444（3.128,13.278）times higher for hypertension and central obesity defined by waist circumference,waist-to-height ratio,and waist-to-hip ratio,respectively.The risk of kidney damage was 2.640（1.807,3.857）,3.028（1.703,5.385）,3.801（1.684,8.580）and 4.149（1.872,9.195）times higher in the control group when only hypertension was present and obesity was not defined as BMI,waist circumference,waist-height ratio,and waist-to-hip ratio,respectively.The risk was2.210（1.079,4.523）,2.339（1.255,4.362）,2.355（1.091,5.083）and 3.097（1.433,6.696）times greater than in the control group when obesity,as defined by BMI,waist circumference,waist-to-height ratio,and waist-to-hip ratio were present without hypertension.All of them were lower than those with hypertension and no obesity.In a gender subgroup analysis,women with both hypertension and general obesity had a3.293（1.858,5.835）fold greater risk of kidney damage than the control group,while men had a 5.880（2.738,12.629）fold increased risk.The risk of kidney damage was7.040（3.285,15.088）,11.247（2.735,46.258）,8.109（2.921,22.507）times in men with combined hypertension and central obesity defined by waist circumference,waist height ratio,and waist-hip ratio,respectively.The risk of female was 3.162（1.499,6.671）,3.218（1.378,7.515）and 5.037（1.812,14.004）times,respectively,which were lower than that of male.In the further interaction analysis,all the additive interaction analysis was not statistically significant,and the interaction relative excess hazard ratio（RERI）and interaction attribution ratio（AP）contained 0 95%confidence intervals,and the interaction index（S）contained 1 95%confidence interval.In male population,the risk of kidney damage caused by hypertension combined with central obesity has a positive multiplicative interaction,that is,when hypertension and central obesity（defined by waist circumference,waist height ratio and waist-hip ratio）co-exist,the risk of kidney damage is significantly greater than the total risk of kidney damage caused by hypertension and central obesity alone.Positive multiplicative interaction was observed in the risk of kidney damage in female hypertension combined with general and central obesity（defined as waist circumference,waist height ratio and waist-hip ratio）.Conclusion:Hypertension combined with central obesity（defined by waist circumference,waist-to-height ratio,and waist-to-hip ratio）had a positive multiplicative interaction but no additive interaction with the risk of renal impairment in both male and female rural populations in northeast China.Hypertension has a greater impact on the risk of kidney damage than normal or central obesity.Compared with female hypertension patients,male hypertension patients should pay more attention to the prevention of central type obesity,in order to prevent the occurrence and development of kidney damage.