Risk factors for cardiovascular disease in chronic spinal cord injury patients.
To establish whether the reported increased cardiovascular (CV) morbidity in spinal cord injury (SCI) patients is due to increased levels of established CV risk factors, we assessed overall CV risk in 102 consecutive patients aged 25-64 by calculation of a 'risk factor score' (RFS) derived from the MRFIT study (age, diastolic blood pressure (DBP), total cholesterol (TC) level, cigarettes/day, sex), obtaining a percentile position amongst an age and sex matched peer group from the 1983 Australian Risk Factor Prevalence Study. Chronic SCI patients had a very low overall percentile position of risk of 26.03 + 15.06 (mean +/- S.D.) and those patients with SCI for greater than 10 years had only a slightly higher risk position of 33.16 +/- 29.66. The low relative risk in SCI patients was due mainly to significantly lower DBP levels (67 +/- 13 mm hg), as TC levels (5.38 +/- 1.60 mmol/L) and cigarette consumption (31% smokers, mode 11-20/day) were similar to the control population (83 +/- 12 mmHg, 5.68 +/- 1.2 mmol/L, 28% smokers, mode 11-20/day, respectively). As other known risk factors such as lipoprotein cholesterol fractions were not included in the RFS index, these were measured in 327 consecutive SCI patients. HDL cholesterol levels, which are negatively correlated with CV risk, were significantly lower in SCI patients (1.12 +/- 0.30 mmol/L) compared to controls (1.35 +/- 0.35 mmol/L) and those patients more than 10 years post SCI had still lower levels (1.02 +/- 0.40). These data suggest that the reported increased incidence of CV disease in SCI patients is unexplained by increases in BP, TC or smoking. However, low HDL levels may contribute to CV risk and the role of other risk factors such as increased vascular reactivity remain to be established.