Increased laboratory testing of trauma patients

A significant increase in the use of blood tests for the management of trauma patients has had little overall effect in terms of survival following trauma, or the length of time those who survive have to spend in hospital. 

This is a headline finding from a recently published study examining the clinical impact of blood testing, particularly the associated iatrogenic blood loss, among patients admitted urgently to hospital following traumatic injury. Investigators compared two cohorts of injured patients admitted to a level 1 trauma center in Los Angeles. 

The first comprised all 384 patients admitted during a 2-month period (March and April) in 2004, and the second comprised all 360 patients admitted during the same period 5 years later in 2009. Analysis of patient records confirmed that there was no significant difference between the two cohorts in terms of demographics, severity of illness and clinical condition on admission. 

Outcome, in terms of mortality and length of time in hospital, was also not significantly different. Despite the similarity in clinical condition and injury severity, blood testing was significantly more frequent among patients admitted in 2009. Mean number of blood tests per patient in 2004 was 21.2 ± 32.5 compared with 33.0 ± 44.4 in 2009. 

For that subset of trauma patients who were admitted to intensive care (70 in 2004 and 107 in 2009) the increase in blood testing was equally evident: mean number of tests per ICU patient in 2004 was 64.7 ± 55.6 compared with 83.2 ± 72.1 in 2009. The tests most commonly requested in order of request frequency were: chemistry profile, full blood count, coagulation, arterial blood gases and toxicology/drug level. 

The proportion of types of blood test remained the same in 2009, as had been the case in 2004. Increased use of arterial blood gases exemplifies the trend for all tests. In 2004 just a quarter (25.7 %) of ICU patients had more than one arterial blood gas analysis per day compared with nearly a half (43.9 %) of all ICU patients in 2009. 

Investigators estimated that blood loss per patient due to testing was 144.4 ± 191.2 mL in 2004 compared with 187.3 ± 265.1 mL in 2009. For ICU patients, who were tested more frequently, the blood loss per patient was 329.7 ± 351 mL in 2004 compared with 435 ± 346 mL in 2009. 

The study provided some evidence that this increased loss of blood contributed to anemia. Anemia was more prevalent and of longer duration among the 2009 cohort, despite no significant difference in admission hemoglobin between the two groups. Red-cell transfusion was more frequent in the 2009 cohort. The financial burden of increased testing was estimated. 

There was a 25 % increase in charges due to laboratory tests for trauma patients admitted to hospital in 2009 compared with those admitted in 2004; for those admitted to intensive care the increase in costs was estimated to be 36 %.