(1) Background: The performance of estimated glomerular filtration rate (eGFR) equations in the Asian population has been widely questioned. The primary objective of this study was to gather evidence regarding optimal GFR equations in Asia for various age groups, disease conditions, and ethnicities. The secondary objective was to see whether the equations based on the combination of creatinine and cystatin C biomarkers if employed are satisfactory across different age groups and disease conditions in various ethnicities in Asia compared to those based on either of the single biomarkers. (2) Methods: Validation studies that had both creatinine and cystatin C-based equations either alone or in combination, validated in specific disease conditions, and those which compared the performance of these equations with exogenous markers were eligible only. The bias, precision, and 30% accuracy (P30) of each equation were recorded accordingly. (3) Results: Twenty-one studies consisting of 11,371 participants were included and 54 equations were extracted. The bias, precision, and P30 accuracies of the equations ranged from −14.54 to 9.96 mL/min/1.73 m², 1.61 to 59.85 mL/min/1.73 m², and 4.7% to 96.10%. The highest values of P30 accuracies were found for the JSN-CKDI equation (96.10%) in Chinese adult renal transplant recipients, for the BIS-2 equation (94.5%) in Chinese elderly CKD patients, and Filler equation (93.70%) also in Chinese adult renal transplant recipients. (4) Conclusions: Optimal equations were identified accordingly and it was proven that combination biomarker equations are more precise and accurate in most of the age groups and disease conditions. These can be considered equations of choice for the specific age groups, disease conditions, and ethnicities within Asia.

Background: Proton pump inhibitors (PPIs) like esomeprazole (ESMP) are first-line therapies for acid-related symptoms in GERD. However, potassium-competitive acid blockers (PCABs) such as Vonoprazan (VPZ) are emerging alternatives. Comparative data on symptom relief and adverse drug reactions (ADRs), especially among South Asian populations, remain limited, despite the high local prevalence of GERD. Objectives: This study aimed to compare the efficacy in symptom relief and the safety profile, including adverse drug reactions (ADRs), of vonoprazan (VPZ) versus esomeprazole ESMP) in patients with gastroesophageal reflux disease (GERD). Methodology: In this cross- sectional observational study, 1,208 clinically diagnosed GERD patients were equally assigned to receive VPZ (20 mg/day) or ESMP (40 mg/day) for ≥4 weeks. The treatment allocation was non-randomized and based on routine clinical care. The severity of symptoms was assessed using a 9-item Likert scale, while perceived improvement and ADRs were evaluated through a validated questionnaire. Analysis included chi-square tests, Welch’s t-tests, and multivariable regression. Results: VPZ users had significantly lower mean GERD-TEST scores (16.9 ± 2.9) than the Esomeprazole group (21.1 ± 3.0; p < 0.001), representing a large effect size (Cohen’s d = 1.40) and a 28% relative reduction (Δ -4.21, 95% CI: -4.50 to -3.92). Overall, ADR incidence was lower with VPZ (35.8%) than with ESMP (48.3%; p < 0.001). Specific ADRs such as fatigue (8.9% vs 16.7%; p < 0.001), diarrhea (13.6% vs 19.4%), and nausea (5.6% vs 10.1%) were less frequent with Vonoprazan. Multivariable analysis showed that higher BMI (kg/m²) reduced ADR odds with VPZ (OR 0.62; p = 0.02); conversely, female sex (OR 1.14; p = 0.03) and smoking showed a trend toward increased ADRs with ESMP. Conclusion: VPZ offers superior symptom control and a favorable safety profile compared with ESMP. These findings support the potential use of VPZ as a preferred therapeutic alternative in GERD management.