Time Trends in Atrial Fibrillation-Associated Stroke and Premorbid Anticoagulation: Population-Based Study and Systematic Review.

Background and Purpose- Prevalence of atrial fibrillation (AF) is increasing, but the impact on overall burden of stroke is uncertain, as is the proportion that could be attributed to under anticoagulation. We did a population-based study of AF-associated stroke and a systematic review of time trends in other stroke incidence studies and of rates of premorbid anticoagulation. Methods- The proportion of incident strokes with associated AF was determined in the OXVASC (Oxford Vascular Study; 2002-2017) and in other prospective, population-based stroke incidence studies published before December 2017. Proportions were pooled by Mantel Haenszel methods, and the pooled percentage of cases with premorbid anticoagulation was determined. Analyses were stratified by the age of study population, mid-study year, country, and ethnicity. Results- Of 1928 patients with incident ischemic stroke in OXVASC, 629 (32.6%; 95% CI, 30.5-34.7) were AF associated, consistent with the pooled estimate from 4 smaller studies over the same study period (608/1948; 31.2%, 30.0-32.4; Phet=0.80). The pooled estimate from all studies reporting premorbid AF over 25 million person-years of observation (1960 onwards; 33 reports) was lower (18.6%, 16.8-20.3) and more heterogeneous (Phet<0.0001), but 62% of heterogeneity was explained by the age of study population, study period, country, and ethnicity. The proportion of incident strokes on premorbid anticoagulation increased over time, both for ischemic stroke in OXVASC (2002-2007: 15.1%, 2008-2012: 19.6%, and 2013-2017: 35.9%; Ptrend<0.0001), and across all studies (P=0.002), but the pooled estimates suggested substantial undertreatment even in the most recent periods (2001-2015: 25.7%, 21.1-30.3 and ≥2010: 31.6%, 18.2-44.9). Conclusions- About 1 in 3 incident ischemic strokes are still AF associated, due partly to low rates of anticoagulation for known prior AF, which therefore represents a major public health opportunity to reduce the burden of stroke.

Recent time trends in incidence, outcome and premorbid treatment of atrial fibrillation-related stroke and other embolic vascular events: a population-based study.

BACKGROUND: Prevalence of atrial fibrillation (AF) is increasing, due partly to the ageing population. The Birmingham Atrial Fibrillation Treatment of the Aged (BAFTA) Trial, published in 2007, provided strong evidence of the effectiveness of warfarin at age≥80 years, but the impact on incidence of AF-related stroke and peripheral embolic vascular events is uncertain. METHODS: We studied age-specific incidence and outcome of all AF-related incident strokes and systemic emboli from 2002 to 2012 in the Oxford Vascular Study. RESULTS: Of 3096 acute cerebral or peripheral vascular events, 748 (24.2%) were AF-related. Of the 597 disabling/fatal incident ischaemic strokes, 369 occurred at age ≥80 years, of which 124 (33.6%) were in non-anticoagulated patients with known prior AF. There was no reduction in incident AF-related events after 2007 at all ages (n=231 vs 211; adjusted RR=1.11, 0.91 to 1.36, p=0.29) or at age ≥80 (137 vs 135, RR=1.15, 0.94 to 1.40, p=0.17). Scope for improved prevention at older ages was considerable. Among 208 patients with incident AF-related events at age ≥80 and known prior AF, only 19 (9.1%) were anticoagulated. Of the 189 patients not anticoagulated, 166 (87.8%) had no major disability prior to the event and 167 (88·4%) had a high embolism risk score, of whom 139 (83.2%) were also at low risk of complications. Yet, 125/167 (74.9%) were dead or institutionalised after the event. Potentially preventable embolic events outnumbered warfarin-related intracerebral haemorrhages by about 15-fold (280 vs 19), rising to 50-fold (189 vs 4) at age ≥80 years. CONCLUSIONS: We found no reduction in incidence of AF-related vascular events since publication of the BAFTA trial. A third of all disabling/fatal strokes occur in non-anticoagulated patients with known prior AF.

Age-specific incidence, outcome, cost, and projected future burden of atrial fibrillation-related embolic vascular events: a population-based study.

BACKGROUND: Prevalence of atrial fibrillation (AF) is >10% at age ≥80 years, but the impact of population aging on rates of AF-related ischemic events is uncertain. METHODS AND RESULTS: We studied age-specific incidence, outcome, and cost of all AF-related incident strokes and systemic emboli from 2002 to 2012 in the Oxford Vascular Study (OXVASC). We determined time trends in incidence of AF-related stroke in comparison with a sister study in 1981 to 1986, extrapolated numbers to the UK population and projected future numbers. Of 3096 acute cerebral or peripheral vascular events in the 92 728 study population, 383 incident ischemic strokes and 71 systemic emboli were related to AF, of which 272 (59.9%) occurred at ≥80 years. Of 597 fatal or disabling incident ischemic strokes, 262 (43.9%) were AF-related. Numbers of AF-related ischemic strokes at age ≥80 years increased nearly 3-fold from 1981-1986 to 2002-2012 (extrapolated to the United Kingdom: 6621 to 18 176 per year), due partly to increased age-specific incidence (relative rate 1.52, 95% confidence interval 1.31-1.77, P=0.001), with potentially preventable AF-related events at age ≥80 years costing the United Kingdom £374 million per year. At current incidence rates, numbers of AF-related embolic events at age ≥80 years will treble again by 2050 (72 974/year), with 83.5% of all events occurring in this age group. CONCLUSIONS: Numbers of AF-related incident ischemic strokes at age ≥80 years have trebled over the last 25 years, despite the introduction of anticoagulants, and are projected to treble again by 2050, along with the numbers of systemic emboli. Improved prevention in older people with AF should be a major public health priority.

Population-based study of acute- and long-term care costs after stroke in patients with AF.

BACKGROUND: New treatments for atrial fibrillation patients have been shown to be effective at reducing subsequent vascular event recurrence. However, there are few data on stroke costs in atrial fibrillation patients to allow the cost-effectiveness of these treatments to be assessed. AIMS: Using data from a population-based study, we assessed the acute and long-term costs of stroke in atrial fibrillation patients. METHODS: Health-care costs one-year before and five-years after stroke were obtained from a large population-based study (Oxford Vascular study). Costs were assessed for the three-months poststroke (acute period) and annually thereafter (postacute period). Annual postacute costs were compared with annual baseline costs. Based on patients' living arrangements, costs of institutionalization after the event were included. RESULTS: A total of 191 strokes occurred in 153 patients with known prior atrial fibrillation. Mean health-care costs after stroke were £10 413 (standard deviation 15 105) in the acute phase, with annual postacute health-care costs nonsignificantly smaller than those incurred before the event (£2400 vs. £3356, respectively; P = 0·198). However, for the 136 strokes surviving past the 90-day acute period, costs were nonsignificantly higher than those incurred in the year before the event (£3370 vs. £2566, respectively; P = 0·333). After stroke, 25 (13%) patients were newly admitted into long-term warden, nursing, or residential care, resulting in annual costs of £6880 (standard deviation 15 600) averaged across the 136 stroke cases surviving past the acute period. CONCLUSIONS: Although annual post acute phase hospital and primary health-care costs in stroke patients with prior atrial fibrillation were not significantly different to those incurred before the stroke, long-term nursing/residential care costs were substantial.