A Method for Estimating 24-Hour Urinary Sodium Excretion by Casual Urine Specimen in Chinese Hypertensive Patients

Calibration of 24-h urinary sodium excretion estimates from fasting morning urine in Chinese populations: a comparative analysis of 2 calibration models and a locally developed model

BACKGROUND

Spot urine collection offers a convenient alternative to the more cumbersome 24-h urine collection. However, the widely recognized estimation models, such as Tanaka and International Cooperative Study on Salt, Other Factors, and Blood Pressure (INTERSALT), have not been adequately adapted for widespread use in the general Chinese population.

OBJECTIVES

This study was designed to evaluate the precision of the Tanaka and INTERSALT calibration models, alongside a locally Zhejiang Province-formulated model, in predicting 24-h urinary sodium (24-hUNa) excretion among the Chinese population.

METHODS

The study comprised 1424 participants, aged 18-69 y, who provided both comprehensive 24-h urine and fasting morning urine samples. The researchers assessed the accuracy of the measured 24-hUNa against the estimates obtained from the Tanaka, INTERSALT, and Zhejiang models. This evaluation was conducted at both population and individual levels, employing a range of statistical techniques, including bias analysis, correlation coefficients, intraclass correlation coefficients, receiver operating characteristic curves, Bland-Altman plots, as well as relative and absolute difference calculations, and misclassification rates.

RESULTS

The measured average 24-hUNa excretion was found to be 165.7 ± 71.5 mmol/24-h. Notably, there was a significant deviation between the estimated and measured values for the Tanaka-adjusted model [-11.7 mmol, 95% confidence interval (CI): -16.7, -6.7 mmol/24-h], indicating a statistically significant difference. In contrast, the deviations for the INTERSALT-adjusted model (0.6 mmol, 95% CI: -4.2, 5.4 mmol/24-h) and the Zhejiang model (0.2 mmol, 95% CI: -4.6, 5.0 mmol/24-h) were nonsignificant. The correlation coefficients for the models were 0.303, 0.398, and 0.391, respectively, with the INTERSALT-adjusted and Zhejiang models showing superior performance at the population level.

CONCLUSIONS

The 3 evaluation models may serve as effective, low-burden alternatives for assessing urinary sodium levels in the population. However, to enhance the accuracy and reliability of predictions at the individual level, further repeated measurements are necessary to minimize measurement errors and augment the validity of the estimations.

Risk factors and a predictive model for left ventricular hypertrophy in young adults with salt-sensitive hypertension

Salt-sensitive hypertension is common among individuals with essential hypertension, and the prevalence of left ventricular hypertrophy (LVH) has increased. However, data from early identification of the risk of developing LVH in young adults with salt-sensitive hypertension are lacking. Thus, the present study aimed to design a nomogram for predicting the risk of developing LVH in young adults with salt-sensitive hypertension. A retrospective analysis of 580 patients with salt-sensitive hypertension was conducted. The training set consisted of 70% (n = 406) of the patients, while the validation set consisted of the remaining 30% (n = 174). Based on multivariate analysis of the training set, predictors for LVH were extracted to develop a nomogram. Discrimination curves, calibration curves, and clinical utility were employed to assess the predictive performance of the nomogram. The final simplified nomogram model included age, sex, office systolic blood pressure, duration of hypertension, abdominal obesity, triglyceride-glucose index, and estimated glomerular filtration rate (eGFR). In the training set, the model demonstrated moderate discrimination, as indicated by an area under the receiver operating characteristic (ROC) curve of 0.863 (95% confidence interval: 0.831-0.894). The calibration curve exhibited good agreement between the predicted and actual probabilities of LVH in the training set. Additionally, the validation set further confirmed the reliability of the prediction nomogram. In conclusions, the simplified nomogram, which consists of seven routine clinical variables, has shown good performance and clinical utility in identifying young adults with salt-sensitive hypertension who are at high risk of LVH at an early stage.

Evaluation of three prediction formulas of 24-hour urinary sodium excretion in Chinese residents: a systematic review and meta-analysis

OBJECTIVE

To determine the appropriateness of three widely used formulas estimating 24-h urinary Na (24hUNa) from spot urine samples in the Chinese population.

DESIGN

Systematic review and meta-analysis.

SETTING

Literature review was conducted to identify studies for estimating 24hUNa using the Kawasaki, Tanaka and INTERSALT formulas simultaneously in PubMed, Embase and the Cochrane library databases. The mean difference (MD) and correlation coefficients (r) between measures and estimates from different formulas were assessed.

PARTICIPANTS

Information extraction and quality assessment were performed in thirteen studies involving 8369 subjects.

RESULTS

Two studies which affected the overall robustness were excluded in the 'leave-one-out' sensitivity analyses. Within the final meta-analysis included eleven studies and 7197 participants, 36·07 mmol/d (95 %CI 16·89, 55·25) of MD was observed in the Kawasaki formula, and -19·62 mmol/d (95 %CI -37·37, -1·87) in the Tanaka formula and -35·78 mmol/d (95 %CI -50·76, -20·80) in the INTERSALT formula; a pooled r-Fisher's Z of 0·39 (95 %CI 0·32, 0·45) in the Kawasaki formula, 0·43 (95 %CI 0·37, 0·49) in the Tanaka formula and 0·36 (95 %CI 0·31, 0·42) in the INTERSALT formula. Subgroup analyses were conducted to explore the possible factors affecting the accuracy of the formula estimation from three mainly aspects: population types, Na intake levels and urine specimen types.

CONCLUSIONS

The meta-analysis suggested that the Tanaka formula performed a more accurate estimate in Chinese population. Time of collecting spot urine specimens and Na intake level of the sample population might be the main factors affecting the accuracy of the formula estimation.

A Method for Estimating 24 h Urinary Sodium and Potassium Excretion by Spot Urine Specimen in Stroke Patients

Spot urine specimens have been used to estimate 24 h urinary sodium (Na) excretion (24UNaV) and potassium (K) excretion (24UKV). However, the validity is limited for 24UNaV and unknown for 24UKV in stroke patients, using the existing formulas. Herein, we developed and validated a new formula for 24UNaV and 24UKV by spot urine specimens in stroke patients. Spot and 24 h urine samples were collected from 970 stroke patients. The models of 24UNaV and 24UKV were developed using stepwise multivariate linear regression in 689 patients. The performance of different formulas was internally validated in 281 patients at the population and individual levels. The obtained new formulas were: (1) estimated 24UNaV (mmol/day): -0.191 × Age + 4.349 × BMI + 0.229 × Spot_Na + 1.744 × Spot_Na/Spot creatinine (Cr) + 41.492 (for male); -1.030 × Age + 2.011 × BMI + 0.143 × Spot_Na + 1.035 × Spot_Na/Spot_Cr + 147.159 (for female); and (2) estimated 24UKV (mmol/day): -0.052 × Age + 0.410 × BMI + 0.031 × Spot_K + 33.280 × Ln (spot_K/spot _Cr) - 5.789 × Ln (spot_Na/spot _Cr) - 1.035 (for male); -0.235 × Age + 0.530 × BMI + 0.040 × Spot_K + 30.990 × Ln (spot _K/spot _Cr) - 7.837 × Ln (spot_Na/spot_Cr) + 4.318 (for female). The new formula obtained the lowest mean bias (5.17 mmol/day for 24UNaV and 0.85 mmol/day for 24UKV) and highest proportion at the cutoff under the ±30% level for the estimation of 24UNaV (59.43%) and 24UKV (70.11%). The new formula provides a meaningful exploration to estimate 24UNaV and 24UKV in stroke patients by using spot urine specimens.