Response to Letter Regarding Article, “Long-Term Mortality After First-Ever and Recurrent Stroke in Young Adults”
We thank Rutten-Jacobs and De Leeuw of their kind remarks on our recent article of long-term mortality after young stroke.1 In this article, we compared the mortality rates of young ischemic stroke patients with the general population using the standardized mortality ratio (SMR). We observed an increased mortality rate for young ischemic stroke patients as did Rutten-Jacobs et al in their previous study.2 We discussed that the SMR in our study was almost twice as high as in their study. In their letter, Rutten-Jacobs and De Leeuw write that it can be problematic to compare SMRs between different study populations as each study population’s SMR is based on its own sets of weights determined by the age, sex, and calendar-year structure of the study. We do agree that it would have been best not to compare the exact SMRs of these 2 different studies because of different study populations.
Rutten-Jacobs and De Leeuw also suggest that there is a difference in the calculation method of the expected number of deaths in comparison to theirs. This seems to be true because in our study, we calculated the expected number of deaths at subgroup level. As a result, the SMR for all, for women and for men, for the recurrent stroke and the Trial of Org 10 172 in Acute Stroke Treatment (TOAST) subgroups were higher than if the calculations had been made as in their study.2
Recalculating the 5-year SMRs in Table 3 of our article1 produces an SMR for all, 3.71; 95% confidence interval, 3.12 to 4.30 (expected number of deaths, 40.9; absolute excess risk per 1000 person-years [AER], 11.22); for all aged 15 to 39 years, 4.30; 95% CI, 2.50 to 6.09 (expected deaths, 5.1; AER, 5.27); for all aged 40 to 49 years, 3.63; 95% CI 3.01 to 4.26 (expected deaths 35.8, AER 14. 07); for men, 3.38; 95% CI, 2.75 to 4.01 (expected deaths, 33.1; AER, 12.84); for men aged 15 to 39 years, 3.62; 95% CI, 1.72 to 5.52 (expected deaths, 3.9; AER, 6.04); for men aged 40 to 49 years, 3.35; 95% CI, 2.69 to 4.01 (expected deaths, 29.3; AER 15.39); for women, 5.14; 95% CI, 3.55 to 6.73 (expected deaths, 7.8; AER, 8.58), for women aged 15 to 39 years, 6.39; 95% CI, 1.96 to 10.81 (expected deaths, 1.3; AER 4.42); and for women aged 40 to 49 years, 4.90; 95% CI, 3.20 to 6.60 (expected deaths, 6.5; AER, 11.43).
Similarly, recalculations in Table III in the online-only Data Supplement1 gives an SMR for the recurrent stroke group, 6.66, 95% CI, 4.67 to 8.65 (expected deaths, 6.5; AER, 26.61); for men with recurrent stroke, 5.85; 95% CI, 3.79 to 7.90 (expected deaths, 5.3; AER, 28.80); for women with recurrent stroke, 10.40; 95% CI, 4.51 to 16.78 (expected deaths, 1.2; AER, 22.55); for the no recurrent stroke group, 3.16; 95% CI, 2.57 to 3.76 (expected deaths, 34.5; AER, 8.74); for men with no recurrent stroke, 2.91; 95% CI, 2.28 to 3.54 (expected deaths, 27.8; AER, 10.12); and for women with no recurrent stroke, 4.22; 95% CI, 2.66 to 5.79 (expected deaths, 6.6; AER, 6.53).
Recalculations in Table IV in the online-only Data Supplement1 gives an SMR for the large-artery atherosclerosis group, 6.96; 95% CI, 4.33 to 9.58 (expected deaths, 3.9; AER, 35.41); for the high-risk source of cardioembolism group, 5.53; 95% CI, 3.32 to 7.74 (expected deaths, 4.3; AER, 25.62); for the low-risk source of cardioembolism group, 1.00; 95% CI, –0.13 to 2.12 (expected deaths, 3.0; AER, –0.01); for the small-vessel occlusion group, 3.42; 95% CI, 2.08 to 4.76 (expected deaths, 7.3; AER, 12.81); for the internal carotid artery dissection group, 0.66; 95% CI, –0.26 to 1.58 (expected deaths, 3.0; AER, –1.36); for the vertebral artery dissection group, 1.25; 95% CI, 0.02 to 2.47 (expected deaths, 3.2; AER, 0.94); for the rare causes other than dissection group, 6.77; 95% CI, 4.06 to 9.48 (expected deaths, 3.5; AER, 21.01); and for the undetermined cause group, 3.41; 95% CI, 2.39 to 4.43 (expected deaths, 12.6; AER, 8.51).
In conclusion, both studies showed an increased risk of death among young ischemic stroke patients compared with the general population, which is why there is a special need for global acts as well as international collaborations between study groups to strike the burden of stroke in young adults.
Karoliina Aarnio, MD
Department of Neurology
Helsinki University Central Hospital
Jukka Putaala, MD, PhD, MSc
Department of Neurology
Helsinki University Central Hospital and Division of Neurosciences
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- © 2014 American Heart Association, Inc.