Aspirin compliance for cardiovascular disease and colorectal cancer prevention in the uninsured population

Aspirin is an effective anti-inflammatory and antiplatelet agent as an irreversible inhibitor of cyclooxygenase. In 2016, the U.S. Preventive Services Task Force recommended aspirin for primary prevention of cardiovascular disease (CVD) and colorectal cancer (CRC) in patients aged 50 to 69 with a 10% or greater 10-year CVD risk. Due to the lack of literature describing compliance with these recommendations in the uninsured patient population, we studied the aspirin adherence for CVD and CRC prevention in several free medical clinics. We investigated the records of 8857 uninsured patients who visited nine free medical clinics in the Tampa Bay Area in 2016-2017. Aspirin compliance was assessed for patients with prior myocardial infarction (MI) or coronary artery disease (CAD). 54% (n=1467) of patients met the criteria to take aspirin for primary prevention of CVD and CRC, but just 17% of these patients aged 50-59 were on the medication. 16% percent of patients aged 60-69 were taking aspirin and significantly more men than women were on aspirin (p=0.025). Of the 306 patients who had prior MI or CAD, 50% were on the medication for secondary prevention. Among the uninsured population, there is low compliance with recommendations for aspirin usage to reduce the risk of CVD and CRC. This study demonstrates that further improvements are needed to increase adherence to current guidelines and address barriers uninsured patients may face in maintaining their cardiovascular and colorectal health.

54 is high certainty that the net benefit is moderate or there is moderate certainty that the net 55 benefit is moderate to substantial", whereas Class C recommendations indicate "at least 56 moderate certainty that the benefit is small" and to offer the intervention to "selected patients    116 had a 10% or greater 10-year Framingham risk score, the threshold to take aspirin for primary 117 prevention of CVD and CRC. Three hundred six patients (3.5%) had a history of MI or CAD, 118 meeting AHA/ACCF criteria to use aspirin for secondary prevention of CVD (Fig. 1).
119 Fig. 1 Details of sample development. 120 121 Of the 1467 patients who met the criteria to take aspirin for primary prevention of CVD and 122 CRC, 751 were aged 50-59 and 716 were aged 60-69. In the 50-59 year age group, 16.8% 123 (126/751) of the patients were taking aspirin, and sex, race, or employment status did not differ 124 between aspirin users and non-users. In the 60-69 year age group, 15.5% (111/716) were taking 125 aspirin (Fig. 2), significantly more men than women were taking aspirin (p=0.025), and 126 Caucasians were more likely to be taking aspirin than patients of other races (p=0.011) ( 134 (105/219) of patients who had a history of CAD were taking aspirin (Fig. 2). The effects of sex 135 and race on compliance with aspirin recommendations were not statistically significant. Among 136 patients with a history of CAD, those who were currently employed were more likely to be 137 taking aspirin (p=0.04) ( Table 2).

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139   154 Previous studies reported underutilization of aspirin for the primary and secondary prevention of 155 CVD in the general population. One study reported 40.9% of patients were told by their 156 physician to take aspirin for primary prevention, with 79% complying. Comparably, 75.9% of 157 patients were told by their physician to take aspirin for secondary prevention, with 89.9% 158 complying [12]. Despite the seeming underuse of CVD risk score calculators, such as the 159 Framingham risk score calculator, providers may be considering the risk of GI bleeding and 160 hemorrhagic stroke associated with an aspirin regimen when evaluating patients. A low dose 161 aspirin regimen was found to increase the risk of GI bleeding by 58% and hemorrhagic stroke by 162 27% in patients using the medication for primary prevention of CVD [17]. Consideration of the 163 bleeding risks could play a role in the under-prescription of aspirin.

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165 Within the general population, aspirin use is lower than that recommended by current guidelines.
166 Our results showed that uninsured patients had even lower rates of use than the general 167 population, indicating room to improve compliance to guidelines. These findings bring up the 168 question of why uninsured patients have suboptimal rates of aspirin use. Lack of health insurance 169 and a low socioeconomic status have been associated with medication non-adherence [18,19].
170 However, there is limited information regarding provider prescribing patterns in free medical 171 clinics. A combination of poor medication adherence and provider prescribing patterns could be 172 a possible explanation for the discrepancy between aspirin use among the uninsured and general 173 patient populations. 174 175 We also found inappropriate use of aspirin. Among patients in our study, 2.5% (172/6919) did 176 not meet guideline criteria but were taking aspirin. This result contrasts with that from a previous 177 study using a national database, which reported that 11.6% of patients were inappropriately 178 taking aspirin for primary prevention of CVD [20]. However, that study used older guideline