An analysis of routine blood testing of British army pilots

The purpose of the study was to ascertain what had been discovered in the 15 yr that the British Army has been conducting a program of routine blood testing on its pilot population. These results were to be analyzed with respect to the causes of medical retirement, change of flight status on medical grounds, accidents, incidents, and sudden incapacitation in flight.

Data were collected from the records of 408 aircrew and comprised 1213 records of test batteries. Each battery consisted of: complete blood count, erythrocyte sedimentation rate, urea and electrolytes, liver function tests, fasting glucose, thyroid function tests, and fasting lipids. Altogether 8,491 tests were considered. They were analyzed for degree of abnormality, subsequent action, resultant diagnoses, and therapeutic interventions.

The positive predictive values for the tests ranged between 2% and 33%. The overall percentages of tests that resulted in a diagnosis were between 0.08% and 3.5%, and therapeutic intervention between 0.08% and 3.4%.

No evidence to support the continuation of routine blood testing was found other than in the case of lipid estimation. Although this had the highest diagnostic yield, abnormal results were dealt with in an inconsistent manner. Further, the testing was shown to have no predictive value in any of the adverse pilot outcomes mentioned above. Recommendations to alter future practice have been made and accepted in full by the Aviation Medicine hierarchies of all three UK Services.