The data used in the present study stems from the project entitled: "Prevention of diseases and illnesses in patients with arterial hypertension in the context of Primary Health Care: chronic kidney disease in focus"8. This is a cross-sectional study with a representative sample of hypertensive and/or diabetic individuals with no previous diagnosis of chronic kidney disease, in PHC in a city in the southeastern region of Brazil, carried out from August 2017 to April 2018. The project was approved by the Human Research Ethics Committee of the Universidade Federal de Viçosa (CEP/UFV), under legal opinion number 1,203.173 (CAAE: 47356115.3.0000.5153). All ethical precepts of Resolution No. 466/2012 of the National Health Council were followed and the informed consent form was signed by all study participants.
The project participants were recruited from 16 of the 18 Basic Health Units of this city. The inclusion criteria for the participants were the following: to be aged over 18 years, to have been diagnosed with AH and/or DM, to be assisted by the Family Health Strategy, and to agree to participate in the study after clarification. Participants who did not attend or could not come to the collection site on the scheduled day, pregnant women, individuals with severe clinical conditions requiring specialized care, and those with a history of alcohol and/or drug abuse were excluded.
A representative sample was collected from the city's Basic Health Units. Conglomerate sampling was used in two stages as follows: in the first stage, the health centers were sampled; in the second stage, patients under treatment in these centers were selected. The random selection of patients was carried out using the patient records of these health centers.
To calculate the project sample, the population of 6,624 hypertensive and/or diabetic individuals registered and assisted by the PHC units in 201, 50% of estimated prevalence of the phenomenon, 5% margin of sampling error, 50% of conglomerate effect, 10% of refusals and/or losses, 20% to control for confounding factors, and 95% confidence level were all considered. The sample calculation was performed using the Statcalc program from Epi-Info® version 7.2 and the resulting sample size consisted of 719 individuals. A total of 841 individuals were recruited. In the present study, 91 individuals older than 75 years, 78 individuals with albuminuria ≥30mg, and 35 individuals who did not participate in all stages of data collection were excluded, resulting in a final sample of 637 individuals for the present analysis (229 men and 408 women).
Data collection was carried out through the application of questionnaires and the evaluation of anthropometric, clinical, and biochemical parameters. The questionnaire contained sociodemographic, clinical, and living habits variables and was based on previous studies(9,10). Systolic and diastolic blood pressures were measured with previously calibrated aneroid manometers and according to the procedures recommended by the Brazilian Guidelines on Arterial Hypertension3.
The collection and analysis of biological materials (blood and urine) were performed in a commercial laboratory, which was licensed for this purpose, using commercial kits and reference standards of the laboratory's own results. The participants were instructed on the procedures for collecting the first urine sample collected in the morning and on how to follow overnight fasting for the twelve hours preceding the blood collection. The biochemical tests performed were the following : fasting glucose (mg/dL), glycosylated hemoglobin (%), triglycerides (mg/dL), total cholesterol and fractions (mg/dL), phosphorus (mg/dL), calcium (mg/dL), serum albumin (mg/dL) and urinary creatinine (mg/dL) and albumin (mg/dL).
The measurement of albuminuria was performed based on the urine albumin-to-creatinine ratio in urine samples collected in the morning and analyzed by the nephelometric method. After excluding the individuals who presented a level of albuminuria greater than or equal to 30mg/g, the remaining participants were divided into three groups according to the tercile of albuminuria (≤3.0, 4.0 - 7.0, ≥8.0). The highest tercile (≥8mg/g) was adopted as the threshold of the albumin/creatinine ratio in urine, classifying these individuals as presenting LGA, without corrections for gender
The Framingham Risk Score (FRS) was used to assess the risk of an individual presenting cardiovascular events in the next 10 years³. It is calculated based on the following variables: age, gender, total cholesterol, HDL-C, systolic blood pressure, and smoking¹¹. Based on the FRS, individuals are categorized into three groups, namely: high-risk (> 20%), intermediate-risk (10-20%), and low-risk (<10%) patients. An FRS ratio that is ≥ 20% is considered equivalent to coronary heart disease risk, and primary prevention is recommended for individuals in this category11.
To characterize the population regarding the variables under study, a descriptive analysis was performed by estimating the absolute and relative frequencies, means, medians, standard deviations, and interquartile ranges. Pearson's chi-square test was used to verify the associations between the categorical variables. The normality of continuous variables distribution was tested using the Shapiro Wilk test. According to the normality test results, either Student's t-test (parametric) or the Mann Whitney test (nonparametric) was used.
To compare demographic and clinical characteristics between groups according to albuminuria terciles, ANOVA stratified by gender was performed. A logistic regression analysis was used to evaluate the odds ratio for the highest tercile of albuminuria and FRS having as covariates those that presented p<0.200 in the previous analysis. The odds ratio and their respective 95% confidence intervals were used to assess the magnitude of the associations. The comparison of FRS with albuminuria terciles was analyzed using an ANOVA. The distribution of categorized FRS (low, medium, and high-risk) by albuminuria terciles were analyzed by the Chi-squared test. All tests were two-tailed, and p-values that were <0.05 were considered to indicate statistical significance. All analyses were carried out using the Statistical Package for the Social Sciences, version 22; SPSS Inc. Chicago, USA.