A bstract Background: Reference intervals for coagulation parameters are influenced by demographic and biological factors that vary across populations. In Nigeria, laboratory reference intervals are often derived from non-African populations, potentially leading to diagnostic inaccuracies. Objectives: This study aimed to establish population-specific reference intervals for coagulation parameters and assess variations by sex and ABO blood group in a healthy Nigerian adult population. Materials and Methods: This cross-sectional study was conducted among 976 healthy adults (488 males and 488 females) from three Nigerian geopolitical zones/regions. Coagulation parameters—including prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (APTT), APTT ratio, thrombin time (TT), fibrinogen, and platelet indices—were analyzed following Clinical and Laboratory Standards Institute (CLSI) EP28-A3C guidelines. Reference intervals were established using CLSI-recommended nonparametric methods, defining the central 95% reference interval (2.5th–97.5th percentiles). Data normality was assessed using the Shapiro–Wilk test, and group comparisons utilized Kruskal–Wallis tests with Dwass–Steel–Critchlow–Fligner post hoc analyses and Mann–Whitney U tests for sex differences ( P < 0.05). hered to CLSI EP28-A3C and strengthening the reporting of observational studies in epidemiology reporting standards. Results: Median values were as follows: PT: 13.0 s, INR: 1.15, APTT: 32.8 s, APTT ratio: 1.49, TT: 19.2 s, and fibrinogen: 2.40 g/L. Group O had significantly longer APTT and APTT ratios than non-O groups ( P < 0.01), whereas group AB had higher PT and INR ( P < 0.05). Females had higher fibrinogen levels and platelet indices, whereas males had longer PT, INR, and APTT values. Conclusion: Significant sex- and ABO-related differences exist in coagulation parameters among Nigerians. We recommend the adoption of locally derived, population-specific reference intervals in Nigerian laboratories to improve diagnostic accuracy and patient management.
Ezigbo et al. (Sat,) studied this question.