Hematological Parameters' Reference Intervals in Apparently Healthy People in Saudi Arabia: Systematic Review and Meta-Analysis

Naila Shaheen ¹ Seena Thomas ¹ Areej Al Moghairi ² Ahmed Alaskar ^1*

• ¹ King Abdullah International Medical Research Center (KAIMRC), Riyadh, Saudi Arabia
• ² King Abdulaziz Medical City, Riyadh, Saudi Arabia

The study aimed to undertake a systematic review/meta-analysis of the observational studies conducted in Saudi Arabia to identify the patterns of reported hematological parameters' Reference Intervals (RIs).The literature search was performed using PubMed, and Google scholar. The observational studies that had reported the hematological parameters measured under normal physiological conditions, in apparently healthy subjects were included. Studies conducted on non-healthy subjects, and/or on pregnant women, related to basic science, methodology , physiology, non-physiological state, having co-morbidities were excluded. The studies on pediatric population were excluded from the meta-analysis. The methodological quality was assessed by using standard critical appraisal instruments of the Joanna Briggs Institute (JBI) Critical Appraisal Checklist. R software was used to run the random effect models. Results were reported as weighted mean difference and 95% confidence intervals. The CBC parameter means were compared by gender using independent sample t-test.In total twelve studies were included for systematic review from all regions; Central (n=5), Western (n=5), Southern (n=1), and Northern (n=1). Eight (66%) studies have focused on adults, and four (33.3%) studies reported a sample of adolescents/children. Seven studies were not included in the meta-analysis i.e. three studies had reported only WBC parameters, for two studies only abstract was available, and two were reported in newborns. High heterogeneity was demonstrated for all hematological parameters; RBC/Hb/MCHC (I 2 =100%), MCH/HCT (I 2 =99%), PLT/MCV (I 2 =98%), and WBC (I 2 =90%). The RBC (p=0.009), and Hb (p=0.0006) values were higher in males. PLT (p=<0.0001) were higher in females. The remaining hematological parameters RIs' were not statistically significant.The findings indicate some differences in the hematological parameters' RIs reported across Saudi Arabia. We recommend establishing hematological parameters' RIs based on the Saudi population, to determine when to refer a patient with abnormal counts, and to identify when to request the further diagnostic work-up.