Diagnostic accuracy of urine dipstick for proteinuria category in Japanese workers

Slope of the estimated glomerular filtration rate and its associated factors among individuals with chronic kidney disease in the general Japanese population

BACKGROUND

To suppress the incidence of end-stage kidney disease, we need to identify chronic kidney disease (CKD) patients with a high risk of rapid decline in the estimated glomerular filtration rate (eGFR). However, the current status of eGFR slope and its associated factors in the Japanese population have not been fully elucidated.

METHODS

Among examinees aged 40-70 years in the 2014 Specific Health Checkup conducted by the National Health Insurance in Kobe, Japan (n = 61,985), we prospectively observed 7291 examinees with CKD stage G3 from 2014 to 2018.

RESULTS

Until 2018, 4221 examinees continued to undergo annual SHCs for a total of five checkups per subject and had available records of all necessary data. The median eGFR change was -0.22 ml/min/1.73 m2/year. Only 9.2% of those subjects showed rapid eGFR decline (faster than -2.0 ml/min/1.73 m2/year). Logistic regression analysis identified diabetes, smoking habits, high urinary protein levels, older age, high systolic blood pressure, and low serum low-density lipoprotein cholesterol levels as independent predictors for rapid eGFR decline. Hemoglobin A1c levels did not contribute to the eGFR slope in CKD stage-G3 subjects with diabetes and proteinuria.

CONCLUSION

Most Japanese CKD stage-G3 subjects had a very slow decline in eGFR. A small proportion of CKD individuals who have a predictive factor of rapid eGFR decline should receive considerable attention from a nephrologist.

Combined effects of blood pressure and glucose status on the risk of chronic kidney disease

This study aimed to assess the combined effects of blood pressure (BP) and glucose status on chronic kidney disease (CKD) incidence in young and middle-aged adults. We examined data from 1,297,341 Japanese individuals aged <60 years (60.1% men; mean age 41.4 ± 9.3 years) with no history of CKD at baseline. The interval-censored Cox proportional hazards model with covariates was used. During a median follow-up period of 2.1 years, new onset CKD (estimated glomerular filtration rate <60 ml/min/1.73 m2 and/or proteinuria) occurred in 80,187 participants. In participants without antihypertensive treatment (AHT), the adjusted hazard ratios (95% confidence interval) per 1-standard deviation, that is, 15 mmHg increase in systolic BP for CKD incidence, were 1.08 (1.07-1.09), 1.12 (1.10-1.13), and 1.15 (1.12-1.18) in normoglycemia, borderline glycemia, and diabetes groups, respectively. These ratios were significantly higher in the borderline glycemia and diabetes groups compared with those in the normoglycemia group (interaction p < 0.0001). The interaction between BP and borderline glycemia was evident when the outcome definition was restricted to proteinuria. In participants under AHT, systolic BP was most strongly associated with CKD risk in the diabetes group, although no significant interaction was observed. High BP and high glucose status may synergistically increase the incidence of CKD. Strict BP management may play an important role in the early prevention of CKD in individuals with worse glucose status within the young and middle-aged population. This large-scale longitudinal cohort study showed high BP and diabetes synergistically increased the risk of CKD in individuals without AHT. Strict BP management may play an important role in the early prevention of CKD in individuals with worse glucose status within the young and middle-aged population.

Trace proteinuria detected via dipstick test is associated with kidney function decline and new-onset overt proteinuria: the Japan Specific Health Checkups (J-SHC) Study

BACKGROUND

Microalbuminuria is associated with mortality, cardiovascular disease, and end-stage kidney disease. The association between trace proteinuria (detected via dipstick test) and kidney outcomes is unclear.

METHODS

This nationwide longitudinal study used data from the Japan Specific Health Checkups Study conducted during 2008-2014. The frequency of trace proteinuria (detected via dipstick test) during first two visits was used as an exposure variable (TrUP 0/2, no trace proteinuria; TrUP 1/2, detected once; TrUP 2/2, detected twice), and kidney outcomes were evaluated. The association between the frequency of trace proteinuria and incidence of 1.5-fold increase in serum creatinine levels and overt proteinuria was analyzed using Cox regression analysis. Trajectories of estimated glomerular filtration rate (eGFR) were compared using a mixed-effect model.

RESULTS

Among 306,317 participants, 3188 and 17,461 developed a 1.5-fold increase in serum creatinine levels and new-onset overt proteinuria, respectively, during the median follow-up period of 36.2 months. The adjusted hazard ratio (HR) and 95% confidence interval (CI) for 1.5-fold increase in serum creatinine level in the TrUP 1/2 and TrUP 2/2 groups, compared to TrUP 0/2 group, were 1.23 (1.07-1.42) and 1.39 (1.01-1.92), respectively, and the adjusted HR (95% CI) for overt proteinuria were 2.94 (2.83-3.06) and 5.14 (4.80-5.51), respectively. The eGFR decline rates in the TrUP 1/2 and TrUP 2/2 groups were higher than that in the TrUP 0/2 group (p for interaction < 0.001).

CONCLUSIONS

Trace proteinuria (detected via dipstick test) was associated with subsequent kidney function decline and overt proteinuria in the general population.

Establishment, verification, and application of concentration intervals corresponding to dipstick grades for urinary protein

BACKGROUND

To address the situation that the accuracy of concentration intervals (CI) corresponding to dipstick grades is not given by the manufacturers or literature, we developed a method that determined reasonable dipstick grades with concentration intervals (GCIs) based on the percent agreement (PA) and discussed the GCI application to comparability among currently dipstick tests.

METHODS

By comparing the results of 2 dipstick tests (iChem and KU-500) with the quantitative test (AU5800), the GCIs were verified and established based on the PAs, which were calculated and used as an indicator of GCI's accuracy. The overlap (percent) between the 2 GCIs with the same grade (2 dipstick devices), was calculated and used to evaluate the agreement between their test results.

RESULTS

After verification and adjustment, the GCI and PA combinations for iChem Velocity were as follows: - (<0.1 g/l, 85 %), ± (0.1-0.3 g/l, 66 %), 1+ (0.3-1 g/l, 78 %), 2+ (1-3 g/l, 74 %), 3+ (3-6 g/l, 77 %), and 4+ (≥6 g/l, 84 %). The determined GCI and PA combinations for KU-500 were: - (<0.1.2 g/l, 75 %), ± (0.12-0.5 g/l, 63 %), 1+ (0.5-1.2 g/l, 69 %), 2+ (1.2-3.2 g/l, 76 %), and 3+ (≥3.2 g/l, 82 %). The GCI overlaps between the 2 dipstick devices were - (83 %), ± (45 %), 1+ (56 %), 2+ (82 %), and 3+ or ≥3+ (94 %). The overall overlap was 72 %. Since the overlaps ± (45 %) and 1+ (56 %) were within the overlap reject limit for any grade (70 %), and the overall overlap (72 %) was within the overall overlap reject limit (80 %), the test results of the 2 devices were not comparable.

CONCLUSIONS

GCIs can be verified and established correctly based on PAs, and industry standards for dipstick tests can be established based on GCIs and PAs. Comparability between dipstick devices, historical data, and literature data can be roughly determined based on the overlap.

Sex differences in the evaluation of proteinuria using the urine dipstick test

Background

The urine protein dipstick test is widely used, but false-positive and false-negative results may occur. This study aimed to compare the urine protein dipstick test with a urine protein quantification method.

Methods

The data were extracted using the Abbott Diagnostic Support System, which analyzes the inspection results using multiple parameters. This study included 41,058 specimens tested using the urine dipstick test and protein creatinine ratio from patients aged ≥18 years. The proteinuria creatinine ratio was classified according to the Kidney Disease Outcomes Quality Initiative guidelines.

Results

Urine protein on the dipstick test was negative in 15,548 samples (37.9%), trace in 6,422 samples (15.6%), and ≥1+ in 19,088 samples (46.5%). Among the trace proteinuria samples, A1 (<0.15 g/gCr), A2 (0.15-0.49 g/gCr), and A3 (≥0.5 g/gCr) category proteinuria accounted for 31.2, 44.8, and 24.0% of samples, respectively. All trace proteinuria specimens with a specific gravity of <1.010 were classified as A2 and A3 category proteinuria. In the trace proteinuria cases, women had a lower specific gravity and a higher percentage of A2 or A3 category proteinuria than men. The sensitivity in the "dipstick proteinuria" ≥ trace" group was higher than that in the "dipstick proteinuria ≥ 1+" group within the lower specific gravity group. The sensitivity in the "dipstick proteinuria ≥ 1+" group was higher for men than for women, and the sensitivity in the "dipstick proteinuria ≥ trace" group was higher than that in the "dipstick proteinuria ≥ 1+" group for women.

Conclusion

Pathological proteinuria assessment requires caution; this study suggests that evaluating the specific gravity of urine specimens with trace proteinuria is essential. Particularly for women, the sensitivity of the urine dipstick test is low, and caution is needed even with trace specimens.

Chronic Kidney Disease Patients Visiting Various Hospital Departments: An Analysis in a Hospital in Central Tokyo, Japan

To further improve care for chronic kidney disease (CKD) patients, healthcare providers’ awareness of CKD must be raised. Proteinuria testing is essential for CKD care, and collaboration with specialists is recommended for advanced cases. We reviewed data from the electronic medical records of outpatients at our hospital to analyze the clinical departments visited by CKD patients, and the frequency of proteinuria testing and referrals to nephrologists. We defined CKD as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² or a urine protein concentration (U-pro) ≥ +1. We found that 31.1% of the CKD tests in September 2021 were performed in clinical departments other than internal medicine. Furthermore, within 1 year, 68.0% of CKD patients identified in September 2020 underwent a urine dipstick test, and 33.7% underwent a quantitative test for urinary protein or albumin. Additionally, 27.5% of individuals with an eGFR < 30 mL/min/1.73 m² or U-pro ≥ +1 identified by non-nephrology departments in September 2020 visited the nephrology department within 1 year. Repeated assessments of these quality indicators may be useful for progress management in improving CKD care. Because CKD patients visited various departments in our hospital, campaigns to raise CKD awareness must reach a wide range of healthcare providers in hospitals.

Comparison of dipstick and quantitative tests for proteinuria and hematuria in middle-aged, male Japanese employees: A single-center study

BACKGROUND AND AIMS

The early and reliable detection of chronic kidney disease is important. In the present study, we aimed to compare the diagnostic results for proteinuria and hematuria between the dipstick test used in primary occupational health examinations and the quantitative tests used in more thorough examinations in clinics.

METHODS

We conducted a single-center observational study of male staff (N = 573) at Kagoshima University who underwent a health examination in 2017. Both dipsticks and biochemical methods were used to assess proteinuria and hematuria.

RESULTS

For the dipstick test, the sensitivity, specificity, and positive predictive value were 55.6%, 92.4% and 10.4% for proteinuria, and 64.3%, 98.3% and 66.7% for hematuria, respectively. Four participants for whom false-negative results were obtained using dipsticks for proteinuria, and two of these had 3+ urinary glucose.

CONCLUSION

Qualitative tests for proteinuria and hematuria had low sensitivities and positive predictive values. Therefore, for the early and reliable detection of chronic kidney disease, the use of quantitative urine tests should be considered during occupational health examinations.

Association of proteinuria with incident atrial fibrillation in the general Japanese population

BACKGROUND

Although proteinuria has been associated with incident atrial fibrillation (AF) in Western countries, the association has not been investigated in the general Japanese population.

METHODS

Participants aged ≥40 years who underwent the Japanese specific health check-up in Kanazawa City in 2013 and who completed a urine dipstick test were included in this study. Exposure was considered as presence or absence of proteinuria (≥1+). The outcome was incident AF confirmed by 12-lead electrocardiography. The Cox proportional hazard model was used to compute hazard ratio (HR) of proteinuria (≥1+) for incident AF after adjustment for traditional risk factors. We also completed stratified analyses by baseline characteristics.

RESULTS

A total of 37,910 participants aged ≥40 years were included (mean age: 72.3 years, male sex: 37%). Proteinuria ≥1+ was observed in 2.765 (7.3%) participants. During a median follow-up period of 5 years, 708 incident AF cases were observed. Proteinuria ≥1+ was associated with incident AF (HR, 1.47: 95% confidence interval, 1.18-1.84) after covariate adjustment. Stratified analysis demonstrated that the association of proteinuria with AF was stronger in participants <75 years [HR 1.89 (95% CI 1.32-2.70)] compared with those ≥75 years [HR 1.27 (95% CI 0.95-1.69)] (interaction p-value=0.02).

CONCLUSIONS

Proteinuria was significantly associated with incident AF in the general Japanese population. The evaluation of proteinuria using urine dipstick test may be useful in the evaluation of incident AF, especially in younger general population.

Increased body mass index above the upper normal limit is significantly associated with renal dysfunction among community-dwelling persons

PURPOSE

Body mass index (BMI) is a simple index of weight-to-height that is commonly used to classify people as underweight, overweight or obesity, and high BMI has been clearly linked to increased risk of illness in adults. However, few studies have examined the significance of upper normal weight as a risk factor for the development of chronic kidney disease (CKD) in the general Japanese population.

METHODS

We conducted a prospective cohort study designed as part of the Nomura study. We recruited a random sample of 421 men aged 67 ± 10 (mean ± standard deviation; range 24-95) years and 565 women aged 68 ± 9 (22-84) years during their annual health examination in a single community. We examined the relationship between quartiles of baseline BMI and renal dysfunction after a 3-year evaluation based on estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations modified by the Japanese coefficient. CKD was defined as having dipstick-positive proteinuria (≥ 1 +) or a low eGFR (< 60 mL/min/1.73 m²).

RESULTS

Of the 986 participants, a total of 134 (13.6%) participants, including 72 (17.1%) men and 62 (11.0%) women, received a new diagnosis of CKD during the study period, and 25 (9.7%), 19 (8.0%), 47 (19.0%), and 43 (17.8%) diagnoses were received in the BMI-1 (BMI, < 20.7 kg/m²), BMI-2 (BMI, 20.7 to 22.5 kg/m²), BMI-3 (BMI, 22.6 to 24.4 kg/m²), and BMI-4 (BMI ≥ 24.5 kg/m²) groups, respectively. Using BMI-2 as the reference group, the non-adjusted odds ratio (OR) (95% confidence interval) for CKD was 2.70 (1.53-4.75) for BMI-3 and 2.49 (1.40-4.42) for BMI-4, and the multivariable-adjusted OR was 2.52 (1.40-4.56) for BMI-3 and 2.30 (1.26-4.22) for BMI-4.

CONCLUSIONS

Increased BMI from upper normal weight is strongly associated with the development of CKD in community-dwelling persons.

Regional variance in the use of urine dipstick test for outpatients in Japan

AIM

The urine dipstick is a simple diagnostic module for detecting proteinuria, haematuria and glycosuria and is favourably accepted in East Asia despite debates regarding its accuracy and target population, claiming that quantitative tests for a high-risk cohort should be more cost-effective. However, the current status of utilizing this test in these countries is not widely known due to lack of extensive data. We aimed to clarify the current nationwide and regional status of utilization of the urine dipstick test in an outpatient care setting and to determine the regional factors associated with adoption of this method.

METHODS

This cross-sectional study used openly accessible data from the national claim database that included the health insurance claims data of the Japanese population in 2017.

RESULTS

In total, 67 125 386 urine dipstick tests were performed compared with 1 862 700 quantitative urine protein tests and 17 544 949 urine sediment microscopy tests. Dipstick tests were employed principally for those who are >65 years old (60.3%) and, although the male population (52.5%) is generally larger, the female population is larger in age of 15 to 39 years and >85 years. Multivariate analysis with several regional parameters revealed that the test was performed more commonly in the areas that accommodate greater elderly population (P < .01).

CONCLUSION

Despite a heated dispute, the urine dipstick test is performed even more frequently than the quantitative biochemical or microscopic sediment tests, especially in regions holding the larger elderly population, which suggests that the test forms a part of geriatric medical care.