Determination of reference intervals from a laboratory database of an academic clinical research unit in a tertiary care teaching hospital and an audit of out of range values.

Background: Abnormal laboratory values are a common reason for the exclusion of participants in clinical studies, increasing the recruitment time and cost during conduct. The use of sample-specific reference intervals (RIs) may help to address this issue. Hence, the present study derived site-specific RIs using the department laboratory database and compare the proportion of "out of range" (OOR) values between the new and the old RIs used by the trial site.

Methods: Institutional ethics committee approval was obtained. Data for hematology and biochemistry parameters were analyzed. Normality was assessed and RIs computed using nonparametric method. Data were partitioned for gender and descriptive statistics applied for demographics. The OOR values based on new RIs were compared with old RIs using Chi-squared tests. Between gender OOR proportions compared using Chi-squared test (significance at < 0.05). Post hoc analysis was performed with Beasley's technique.

Results: Data of 601 participants were analyzed. The median (Inter Quartile Range) age was 22 (47) years and 64.72% were male. New RIs for key parameters were: Haemoglobin (9.3-16.5 g/dl), alanine aminotransferase (11.4-47.74 U/I), aspartate aminotransferase (8.8-58 U/I), total bilirubin (0.27-1.4 mg/dl), and creatinine (0.59-1.36 mg/dl). Post partitioning, the RI for hemoglobin (g/dl) was lower (8.72-15.72) in females. The proportion of OOR values were lower with new RIs relative to old laboratory RIs ( < 0.0001).

Conclusion: A reduction in the proportion of OORs and a change in the upper and lower bound laboratory intervals with new RIs emphasize the need for sample-specific ranges to prevent unnecessary exclusions of volunteers from trials.