Results of a large study contradict the view that having sickle cell trait increases a person’s risk of death.
Health records of nearly 50,000 active-duty US Army soldiers showed no significant difference in the risk of death between soldiers who had sickle cell trait and those who did not.
The risk of exertional rhabdomyolysis (ER) was 54% higher among soldiers with sickle cell trait than those without it.
But the study suggested that tobacco use, obesity, and taking certain drugs also incur a heightened risk of ER.
Lianne Kurina, PhD, of Stanford University School of Medicine in California, and her colleagues reported these findings in NEJM.
Previous studies have suggested the health consequences of sickle cell trait might be dire, including higher mortality from ER. ER is characterized by the severe breakdown of skeletal-muscle tissue due to extreme physical exertion. The condition has been known to affect athletes and soldiers.
To assess the risk of ER and death among people with sickle cell trait, Dr Kurina and her colleagues reviewed the health records of 47,944 African-American soldiers who served on active duty between 2011 and 2014 and for whom sickle cell status was known.
The team found no significant difference in the risk of death among soldiers with sickle cell trait and those without. The hazard ratio (HR) was 0.99 (95% confidence interval [CI], 0.46 to 2.13; P=0.97).
Sickle cell trait was associated with a significantly higher adjusted risk of ER, with an HR of 1.54 (95% CI, 1.12 to 2.12; P=0.008).
However, the risk of ER was also higher for the following groups:
- Soldiers who used tobacco (HR=1.54, 95% CI, 1.23 to 1.94; P<0.001)
- Those with a body mass index of 30 or higher, as compared to 25 or lower (HR=1.39, 95% CI, 1.04 to 1.86; P=0.03)
- Those who recently used a statin (HR=2.89, 95% CI, 1.51 to 5.55; P=0.001)
- Those who recently used an antipsychotic agent (HR=3.02, 95% CI, 1.34 to 6.82; P=0.008).
Dr Kurina said the reason the results of this study differ from those of previous studies may be better safety for active-duty soldiers.
As of 2003, soldiers who are engaged in strenuous exercise are required to drink plenty of fluids, build up to strenuous exercise gradually, and take regular rests when it’s hot. All of these measures are known to reduce exercise-related fatality rates, regardless of whether individuals have sickle cell trait, the researchers said.
“Another critical difference between our study and the earlier, population-based studies is that, in our study, we knew the sickle cell status of everyone in the population,” Dr Kurina said.
She and her team looked only at soldiers whose sickle cell status was confirmed by blood tests taken during their years of service, instead of from self-reported sickle cell status or past medical history, as had been done in the other studies.
“The most important thing to come out of this study is the really reassuring news that, under conditions of universal precautions against dehydration and overheating, we don’t see an elevation in the risk of mortality in people with sickle cell trait,” Dr Kurina said.
She added that the study’s results call into question the need to screen service members with sickle cell trait, especially with better safety precautions during intense exertion.
