Increased risk of acute coronary syndrome after spinal cord injury: A nationwide 10-year follow-up cohort study.

Increased risk of acute coronary syndrome after spinal cord

injury: A nationwide

10-year follow-up cohort study

Yen-Kung Chen

, Tzu-Jen Hung

, Che-Chen Lin

, Ruoh-Fang Yen

,

Fung-Chang Sung

,Wen-Yuan Lee

,

Chia-Hung Kao

⁎

Thallium scintillation tests and computerized tomography analyses of coronary artery calcifcation have revealed a higher

prevalence of asymptomatic coronary artery disease in spinal cord

injury (SCI) patients [1–4]. Acute coronary syndrome (ACS) is one of

the most common causes of death in patients with cardiovascular disease. 50% of patients diagnosed with a myocardial infarction experienced silent ischemia and did not exhibit any classic ACS

symptoms [5]. However, the incidence and characteristics of ACS in

SCI patients have not been reported and it is uncertain whether they are actually at a higher risk for ACS. This study uses a large cohort representing 99% of Taiwan's population to analyze the incidence of ACS in disabled SCI patients. The results may guide future care of SCI patients and ACS prevention.

This research used the Taiwan National Health Insurance claim data to identify 41,721 patients diagnosedwith SCIs between 2000 and 2009 and 166,884 frequency-matched claimants without SCIs. The risk of SCI patients developing ACSwas measured using a Cox proportional hazard model.

The SCI cohort included 41,721 patients and the comparison cohort included 166,884 patients of the same average age (50.1 y,

p =0.49) and sex ratio (male: 63.1%, p= 1). The proportion of ACSassociated diabetes, hypertension, or hyperlipidemia comorbidities

in the SCI cohort was much higher than in the comparison cohort (p b 0.0001).

The incidence of ACS development in the SCI cohort was 17.33 per 10,000 person-years and was 1.4 times higher than the

comparison cohort (Table 1). Fig. 1 shows the Kaplan–Meier

estimated cumulative incidence curves for the two study cohorts and indicates that the SCI cohort incidence curve is signifcantly greater than that of the comparison cohort (log-rank test, p b 0.001). After adjusting for potential confounding factors, the SCI cohort was

1.24 times more likely to develop ACS than the comparison cohort (HR= 1.24, 95%; CI= 1.11–1.4). ACS risk estimation is valuable for the medical care and rehabilitation of SCI patients.

Table 1 also shows the demographic-specifc and comorbidityspecifc incidence of developing ACS for the two cohorts. Relative to the comparison cohort, younger SCI patients had the highest risk of developing ACS (b40 y, HR = 3.25; 40–59 y, HR = 1.43; ≥60 y, HR=1.06). Men and women in the SCI cohort were more than 1.2 times more likely to develop ACS than the comparison cohort (female, HR=1.26; male, HR=1.23). The SCI cohort was also associated with an increased risk of developing ACS in patients without diabetes (HR = 1.39, 95%; CI = 1.21–1.59), hypertension (HR =1.29, 95%; CI=1.10–1.51), or hyperlipidemia (HR=1.25, 95%; CI=1.10–1.42). Patients with high and low-level SCIs were 1.22 (HR=1.22, 95%; CI=1.04–1.42) and 1.26 (HR=1.26, 95%; CI=1.07–1.48) times more likely to develop ACS, respectively. However, the results suggest that the difference between ACS risk for high and low-level SCIs is not

signifcant.

Surprisingly, this study found that SCI patients older than 60 years have a similar ACS risk as the comparison cohort. Patients with diabetes, hypertension, or hyperlipidemia have a similar risk of developing ACS in the SCI and comparison cohorts. These fndings are

similar to a study by LaVela et al. [6] which suggested that older adult

men with SCIs who have been injured for a long time have a similar prevalence of diabetes and myocardial infarction as uninjured older

adult men. Wilt et al. [7] concluded that SCI patients do not have a

markedly greater risk of carbohydrate and lipid disorders or cardiovascular morbidity or mortality. This may be because patients with diabetes, hypertension, or hyperlipidemia are more likely to encounter early recognition and treatment of risk factors. However, most research has shown a higher prevalence of ACS in younger SCI

patients [1–4,8].

SCI patients without diabetes, hypertension, or hyperlipidemia had an increased risk of developing ACS. Recognizing the potential presence of these conditions and ACS risk in SCI patients is required for early diagnosis and an improved approach to clinical care. Appropriate interventions are usually discussed with these patients to reduce cardiovascular risk and improve longevity and quality of

life.

This study has certain limitations. The NHIRD does not provide detailed patient information such as smoking habits, body mass index, metabolic syndromes, and physical activity, which are major risk factors for ACS. However, the sample was large enough to allow meaningful analysis of ACS in SCI patients. Age and gender-matched comparison was used to adjust for possible infuences of ACS on the SCI group.

ACS is more likely to occur in younger SCI patients without

diabetes, hypertension, or hyperlipidemia comorbidities. Therefore, it is suggested that these patients are introduced to ACS prevention strategies.