This cohort study assessed MACE risk according to the treatment modalities of phototherapy, biologic, and conventional systemic agents. Herein, the phototherapy and biologic cohorts showed a lower incidence of MACE than the control cohort, and the difference in the cumulative incidence remained significant during the 36-month follow-up period. The cyclosporine and mixed conventional systemic treatments were significantly associated with increased MACE risk. Methotrexate was not associated with MACE in this study.
The biologic cohort showed the lowest incidence of MACE among all the cohorts. In the present study, the incidence of MACE in the biologic cohort was 3.5 per 1,000 PYs. This finding is similar to that of other studies that showed that biologic therapies were associated with lower CV risk than other anti-inflammatory treatments.12-14 A study conducted in Denmark showed that the incidence was 3.49 per 1,000 PYs for a composite CV endpoint in patients with psoriasis treated with TNF-α inhibitors.9 This is also comparable to the result of a study based on data from the Psoriasis Longitudinal Assessment and Registry, that is, 3.6 per 1,000 PYs in patients with psoriasis treated with biologics (n = 7,476) or conventional systemic therapies (n = 2,019).15
In this study, no coronary arterial disease was recorded in patients treated with biologics. . One cardiac arrest case (0.1%) and 10 stroke cases (0.6%) were associated with biologic treatment, and both showed the lowest incidence rates (0.2 and 1.8 per 1,000 PYs, respectively). More than half of MACE in the biologic cohort were observed within 1 year (55%), which was higher than that in the control cohort (35%). The difference in the incidence of composite CV outcomes between the biologic and control cohorts was the greatest in the group aged ≥60 years (12.1 vs. 26.8 per 1,000 PYs), suggesting that the CV protective effect of biologics could be more potent in older individuals. In addition, the most significant MACE risk reductions were observed 3 years after biologic initiation compared to those after conventional systemic treatment (P = .001). This result implies that biologics that target specific cytokines associated with psoriatic inflammation16 may contribute to reducing MACE. However, further investigation with prolonged study periods for individual biological drug classes is required to clarify the association between biologic treatment and MACE risks.
In the present study, the phototherapy treatment was possibly associated with decreased MACE risk. Specifically, the cumulative incidence of MACE was significantly lower with phototherapy than in the control cohort during the study period (P < .001). In addition, the phototherapy cohort showed a lower incidence rate of acute coronary syndrome and stroke than the control cohort (0.2 and 4.7 per 1,000 PYs, respectively). However, based on multivariate Cox regression analyses, phototherapy was not associated with decreased MACE risk compared with the control cohort. Preliminary studies have shown that phototherapy may reduce some inflammatory cytokines; however, there is little evidence regarding a decreased CV risk.17 Our results suggest that phototherapy may have a positive impact on CV risk in patients with psoriasis.
Methotrexate was not associated with MACE in this study. This result differs from results of previous studies that reported an association between methotrexate treatment and reduced CV risk among patients with inflammatory diseases.18,19 However, our result may indicate that methotrexate treatment in patients with moderate-to-severe psoriasis may reduce the MACE risk to at least a level comparable to that in patients with mild disease. This is due to the fact that patients with severe psoriasis show higher CV risk than those with mild disease.20 In addition, the assessment of CV endpoints alone reveals that the methotrexate cohort has the lowest incidence among all the study cohorts in the groups aged ≤60 years. Also, coronary arterial disease and cardiac arrest were not related to methotrexate treatment in the present study. Further research is still needed on the effect of methotrexate on CV events.
Treatment with cyclosporine or mixed conventional systemic agents was associated with a significant increase in the incidence of MACE after adjusting for sex, age, and baseline comorbidities. Although the cyclosporine cohort showed a lower incidence of CV outcomes than the control cohort (7.6 vs. 8.4 per 1,000 PYs), caution is needed to interpret these results. This is because these results may be due to the abrupt decrease in CV events among those in the group aged 41-60 years (2.3 per 1,000 PYs), which had a reduced rate of CV events (n = 2) and was consistent with the tendency of increased CV outcomes in older patients in all the other study cohorts.
Specifically, the mixed conventional systemic cohort showed the highest incidence of cardiac arrest and stroke among the cohorts (1.0 and 14.6 per 1,000 PYs, respectively). Moreover, the stroke risk was significantly higher in the mixed conventional systemic cohort than in the control cohort after adjusting for age, sex, and comorbidities (HR = 1.60; 95% CI = 1.11–2.31). The cyclosporine cohort had a higher rate of ischemic stroke than the control cohort. For all the age groups, the cyclosporine and mixed conventional systemic cohorts showed a greater than three-fold incidence of CV outcomes in the groups aged ≤40 years than in the control cohort. This result may be indicative of the importance of considering CV complications when choosing early systemic anti-inflammatory treatments in younger patients. Previous studies reported that cyclosporine could increase blood pressure,21,22 total cholesterol levels,23 and serum creatinine levels.24 Retinoids, including acitretin, are also associated with increased serum cholesterol and triglyceride levels.25 This study revealed that caution should be exercised when prescribing cyclosporine or acitretin to patients with high CV comorbidities.
Limitations
This study has several limitations. First, because patients with certain risk profiles could have been funneled into specific treatment groups, confounding by indication was possible. To overcome this limitation, we considered baseline comorbidities such as hypertension, dyslipidemia, and renal disease as possible variables that could affect the choice of treatment modality. However, the potentially essential baseline comorbidities such as obesity and liver diseases, social factors, treatment dose, and duration of each treatment modality were not evaluated in this study. In addition, we excluded patients who were diagnosed as having the CV outcomes of interest before the index date for clear assessment of the outcomes. This strict removal, whereas, may result lower incidence in CV outcomes in each cohort than typically expected in patients with psoriasis. Moreover, multivariate Cox regression analyses was not able to done for CV only outcomes due to the small number of outcomes.
Also, age, exposure to each treatment modality, and the baseline characteristics of the patients were analyzed using a fixed model, which limited the accuracy of the allocations of the exposure levels and outcomes in this study. As age is an important confounding factor in CV diseases, we not only included it as a variable for multivariate analysis but also subdivided the patients into three age groups to further exclude the influence of age. The relatively short 3-year follow-up periods also reduced the potential limitation of using age as a fixed variable, although the shorter follow-up period may also constitute a potential limitation of the study.
Additionally, the treatment window, that is, treatment discontinuation after the last claimed treatment, was not considered in this study. This might have been particularly limiting regarding the results in the biologic cohort because the biologics were typically prescribed to patients who had already received phototherapy or conventional systemic agents but had insufficient response to treatment or suffered adverse effects.
Finally, the control group was evaluated from the time of diagnosis; thus, theoretically, the duration of the systemic inflammation related to psoriasis was shorter. This might be another limitation of the study, as it caused difficulty in determining whether the increased CV risk was due to the treatment modality or disease severity. However, although our study could not provide accurate interpretation regarding increased CV risk, our results showed that the effectiveness of some systemic treatment modalities, such as cyclosporine or acitretin, for controlling inflammation was not superior to that of other treatment modalities. Furthermore, we could have evaluated whether adequate systemic treatment might lower the CV risk of patients with moderate-to-severe disease compared with those with relatively short disease durations by including patients recently diagnosed with psoriasis.