Recurrent events and secondary prevention after acute cerebrovascular disease

Sammanfattning: Background Patients who experience a stroke or transient ischemic attack (TIA) are at high risk of recurrent stroke, but little is known about temporal trends in unselected populations. Reports of low adherence to recommended treatments indicate a need for enhanced secondary preventive follow-up to achieve the full potential of evidence-based treatments. In addition, socioeconomic factors have been associated with poor health outcomes in a variety of contexts. Therefore, it is important to assess the implementation and results of secondary prevention in different socioeconomic groups.Aims The aims of this thesis were to assess temporal trends in ischemic stroke recurrence and evaluate the implementation and results of a nurse-led, telephone-based follow-up program to improve blood pressure (BP) and low-density lipoprotein cholesterol (LDL-C) levels after stroke/TIA.Methods In study I, we collected baseline data for unique patients with an ischemic stroke event between 1998 and 2009 (n=196 765) from the Swedish Stroke Register (Riksstroke). Recurrent ischemic stroke events within 1 year were collected from the Swedish National Inpatient Register (IPR) and the cumulative incidence was compared between four time periods using the Kaplan-Meier survival analysis and the logrank test. Implementation (study II) and 1-year results (study III-IV) for the secondary preventive follow-up were studied in the NAILED (Nurse-based Age-independent Intervention to Limit Evolution of Disease) study. Between 1 Jan 2010 and 31 Dec 2013, the baseline characteristics of consecutive patients admitted to Östersund Hospital for acute stroke or TIA were collected prospectively (n=1776). Consenting patients in a condition permitting telephone-based follow-up were randomized to nurse-led, telephone-based follow-up or follow-up according to usual care. Follow-up was cunducted at 1 and 12 months after discharge and the intervention included BP and LDL-C measurements, titration of medication, and lifestyle counseling. In study II, we analyzed factors associated with non-participation in the randomized phase of the NAILED study, including association with education level. In addition, we compared the 1-year prognosis in terms of cumulative survival between participants and non-participants. In study III, we compared differences in BP and LDL-C levels between the intervention and control groups during the first year of follow-up and, in study IV, in relation to level of education (low, ≤10 years; high, >10 years).Results The cumulative 1-year incidence of recurrent ischemic stroke decreased from 15.0% to 12.0%. Among surviving stroke and TIA patients, 53.1% were included for randomization, 35.7% were excluded mainly due to physical or cognitive disability, and 11.2% declined participation in the randomized phase. A low level of education was independently associated with exclusion, as well as the patient’s decision to abstain from randomization. Excluded patients had a more than 12-times higher risk of death within 1 year than patients who were randomized. After 1 year of follow-up, the mean systolic BP, diastolic BP, and LDL-C levels were 3.3 mmHg (95% CI 0.3 to 6.3), 2.3 mmHg (95% CI 0.5 to 4.2), and 0.3 mmol/L (95% CI 0.1 to 0.4) lower in the intervention group than among controls. Among participants with values above the treatment goal at baseline, the differences in systolic BP and LDL-C levels were more pronounced (8.0 mmHg, 95% CI 4.0 to 12.1; 0.6 mmol/L, 95% CI 0.4 to 0.9). In the intervention group, participants with a low level of education achieved similar or larger improvements in BP and LDL-C than participants with a high level of education. In the control group, BP remained unaltered and the LDL-C levels increased among participants with a low level of education.Conclusion The 1-year risk of ischemic stroke recurrence decreased in Sweden between 1998 and 2010. Nurse-led, telephone-based secondary preventive follow-up is feasible in just over half of the survivors of acute stroke and TIA and achieve better than usual care in terms of BP and LDL-C levels, and equality in BP improvements across groups defined by education level. However, a large proportion of stroke survivors are in a general condition precluding this form of follow-up, and their prognosis in terms of 1-year survival is poor. Patients with a low education level are over-represented within this group and among patients declining randomization for secondary preventive follow-up.