The indirect method in the establishment of reference intervals for blood cell parameters in elderly population: A retrospective study

Introduction: Reference intervals (RIs) of blood parameters vary between gender and age. Therefore, it is important to establish specific RIs for the population served. To interpret the reports of elderly population, laboratories use RIs of adults (>18 years old). In calculation of RIs, healthy population is used in direct method while patient data is used in indirect method. This study was carried out to establish RIs for blood cell parameters for elderly population using indirect method.Methods: A retrospective study was carried out using complete blood count (CBC) data of patients >65 years of age. Calculated RIs were compared with RIs defined for adults and with RIs defined for elderly population in five other countries.Results: Data sets in all CBC parameters showed Gaussian distribution thus, parametric approach was adopted to calculate RIs. Calculated RIs of all the CBC parameters for elderly population were similar to those of other countries. RIs calculated for red blood cell count (RBC), haemoglobin (Hb) and packed cell volume (PCV) showed clinically significantly lower values when compared with adult RIs while RIs for other CBC parameters did not show such difference.Conclusions: Patient data can be used to calculate RIs for CBC parameters for elderly population. Elderly population shows clinically significantly lower RBC, Hb, and PCV compared to the adults thus, adult RIs for RBC, Hb, and PCV cannot be used for elderly population.