Stroke and bleeding risk in atrial fibrillation with CHA2DS2-VASC risk score of one: the Norwegian AFNOR study

BACKGROUND AND AIMS

The benefit of oral anticoagulant (OAC) therapy in atrial fibrillation (AF) and intermediate stroke risk is debated. In a nationwide Norwegian cohort with a non-sex CHA2DS2-VASc risk score of one, this study aimed to investigate (i) stroke and bleeding risk in AF patients with and without OAC treatment, and (ii) the risk of stroke in non-anticoagulated individuals with and without AF.

METHODS

A total of 1 118 762 individuals including 34 460 AF patients were followed during 2011-18 until ischaemic stroke, intracranial haemorrhage, increased CHA2DS2-VASc score, or study end. One-year incidence rates (IRs) were calculated as events per 100 person-years (%/py). Cox regression models provided adjusted hazard ratios (aHRs [95% confidence intervals]).

RESULTS

Among AF patients, the ischaemic stroke IR was 0.51%/py in OAC users and 1.05%/py in non-users (aHR 0.47 [0.37-0.59]). Intracranial haemorrhage IR was 0.28%/py in OAC users and 0.19%/py in non-users (aHR 1.23 [0.88-1.72]). Oral anticoagulant use was associated with an increased risk of major bleeding (aHR 1.37 [1.16-1.63]) but lower risk of the combined outcome of ischaemic stroke, major bleeding, and mortality (aHR 0.57 [0.51-0.63]). Non-anticoagulated individuals with AF had higher risk of ischaemic stroke compared to non-AF individuals with the same risk profile (aHR 2.47 [2.17-2.81]).

CONCLUSIONS

In AF patients at intermediate risk of stroke, OAC use was associated with overall favourable clinical outcomes. Non-anticoagulated AF patients had higher risk of ischaemic stroke compared to the general population without AF with the same risk profile.

Prevalence and Incidence Rates of Atrial Fibrillation in Denmark 2004–2018

Purpose

To estimate the prevalence and incidence of atrial fibrillation (AF) in Denmark during 2004–2018 and to investigate whether methodological choices influence these estimates.

Patients and Methods

A register-based cohort study was conducted of all individuals aged ≥18 years in Denmark 2004–2018. The cumulative prevalence of AF at the end of the study period was calculated as the number of AF cases alive with at least one inpatient or two outpatient diagnoses during 1994–2018 divided by the number of Danish residents in 2018. Incidence rates were calculated as the number of annual AF cases with no previous diagnosis in the past 10 years (ie, a 10-year washout period) divided by the person-time contributed by the population free of AF on 1 January in the same calendar year. Furthermore, the influence of varying case definitions was investigated.

Results

The cumulative prevalence of AF was 3.0% in 2018. The incidence rate increased from 391 to 481 per 100,000 person-years (PYs) from 2004 to 2015 (1.7% average annual increase) after which it declined to 367 per 100,000 PYs in 2018 (8.5% average annual decrease). This pattern was observed in both sexes irrespective of age. Methodological choices, particularly the case definition’s strictness and the length of the washout period, had a substantial influence on the reported estimates.

Conclusion

The cumulative prevalence of AF is currently around 3.0% in the Danish population, but the incidence has declined since 2015. As these estimates are influenced by methodological choices, future studies should strive for precise reporting of study methodology.

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Stroke rates in non-anticoagulated individuals with and without atrial fibrillation and one non-sex CHA2DS2-VASc risk factor: a nationwide registry-based cohort (Atrial Fibrillation in Norway – AFNOR)

Background

Stroke prevention is fundamental in the management of atrial fibrillation (AF). However, in patients with intermediate risk of stroke (CHA2DS2-VASc score 2 in women; 1 in men) the net clinical benefit of oral anticoagulant (OAC) treatment is uncertain, as the treatment effect must be carefully balanced against the potential bleeding risk. Moreover, multiple risk factors included in the CHA2DS2-VASc score increase the risk of stroke independent of AF.

Purpose

We aimed to compare rates of ischemic and haemorrhagic stroke between non-anticoagulated individuals with and without AF in a nationwide cohort of individuals at intermediate risk of stroke.

Method

We identified a cohort of non-anticoagulated Norwegian individuals with and without non-valvular AF aged ≥18 years, with one non-sex CHA2DS2-VASc risk factor linking data from the Norwegian Population Registry, Patient Registry, Prescription Database and Cause of Death Registry. AF and comorbidities were identified with minimum three-year look-back period at study start and successively during follow up. Individuals without AF entered the study at date of first registered non-sex CHA2DS2-VASc risk factor while individuals with AF entered at the first date when both AF and first CHA2DS2-VASc risk factor were registered. Individuals with and without AF were followed from study start in 2011 until occurrence of stroke, death, emigration, OAC claim, increased CHA2DS2-VASc score or end of follow-up on December 31, 2018. Rates of ischemic and haemorrhagic stroke were calculated as the number of stroke cases per 100 person-years with 95% confidence intervals (CI).

Results

During 2011–2018, a total of 61,762 individuals with AF at intermediate risk of stroke and no previous OAC use were identified (mean age 63.2±7.6 years (SD); 37% women). In the AF population, a total of 1,304 ischemic strokes were registered during 109,881 person-years, and 127 haemorrhagic strokes during 109,559 person-years. In the corresponding intermediate risk non-AF population, 1,099,655 individuals (mean age 59.5±10.2 years (SD); 49.5% women) were identified, with a total of 6,081 ischemic strokes during 4,037,940 person-years and 3,037 haemorrhagic strokes during 4,022,952 person-years.

The rate of ischemic stroke was 1.19 (95% CI, 1.12–1.25) in AF-patients and 0.15 (95% CI, 0.15–0.15) in non-AF individuals per 100 person-years, corresponding to a rate difference of 1.04 excess stroke cases per 100 person-years in AF patients. The haemorrhagic stroke rate was 0.12 (95% CI, 0.10–0.14) in AF-patients and 0.08 (95% CI, 0.07–0.08) per 100 person-years in non-AF individuals. Similar rate differences were seen in both men and women.

Conclusion

In a nationwide population with one non-sex CHA2DS2-VASc risk factor and without OAC treatment, we found higher stroke rate in AF patients compared to the rest of the population without AF, with a stroke rate difference of ∼1% per year. Haemorrhagic stroke rates were generally low.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): South-Eastern Norway Regional Health Authority

Prevalence and incidence rates of atrial fibrillation in Denmark 2004–2018

Background

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with substantial morbidity and mortality. Its prevalence is currently rising partly due to population ageing. However, reported trends in incidence rates are conflicting, and the comparability of existing reports is limited due to methodological inconsistencies across studies.

Purpose

The main purpose of the current study was to investigate the prevalence of AF in the Danish adult population and time trends in incidence rates from 2004 through 2018. As a secondary purpose, the prevalence and incidence were compared to corresponding Norwegian estimates from 2004 through 2014 derived using the same methodology.

Methods

A register-based study was conducted including all individuals aged ≥18 years in Denmark from 2004–2018. AF cases were identified in the National Patient Register and the Cause of Death Register, which comprise information on all hospital contacts and deaths in Denmark, respectively. The prevalence of AF was calculated as the number of individuals alive at the end of the study period with at least one registered diagnosis from 1994 through 2018 divided by the number of Danish residents aged ≥18 years. Incidence rates were calculated as the number of annual AF cases with no previous diagnosis noted in the past 10 years divided by the person-time contributed by the population free of AF on 1 January in the same calendar year. All incidence rates were standardized according to a Nordic standard population. The comparison of the Danish and Norwegian incidence estimates focused solely on AF hospitalizations and deaths from 2004 through 2014.

Results

The cumulative prevalence of AF was 3.0% in the Danish adult population. The incidence increased from 391 per 100,000 person-years in 2004 to 481 per 100,000 person-years in 2015, after which it declined to 367 per 100,000 person-years in 2018 (Figure 1). On average, the incidence increased by 1.7% annually until 2015 (IRR: 1.017 (95% CI: 1.016–1.018); p<0.001) and then declined by 8.5% (IRR: 0.915 (95% CI: 0.909–0.921); p<0.001). Although the incidence rates generally were higher among men and older individuals, a similar time trend was observed in both men and women irrespective of age. Focusing solely on AF hospitalizations and deaths did not change the interpretation of the results. The comparable Norwegian estimates will be presented at the conference.

Conclusions

The prevalence of AF is currently around 3.0% in the Danish adult population, but the incidence rate has declined steeply since 2015. The observed decline in new cases is promising from a public health perspective and its underlying causes warrant further investigation.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Novo Nordisk Foundation Figure 1

Oral anticoagulation in atrial fibrillation patients at intermediate risk of stroke: a nationwide registry-based cohort (Atrial Fibrillation in Norway – AFNOR)

Background

The effect of oral anticoagulants (OAC) on prevention of stroke must be carefully balanced against the potential risk of bleeding in patients with atrial fibrillation (AF). The net benefit of OAC in AF patients at intermediate risk of stroke remains unclear.

Aim

We aimed to determine whether the rates of ischemic and haemorrhagic stroke differ between users and non-users of OAC in a nationwide cohort of AF patients at intermediate risk of stroke.

Method

We investigated the association between initiation of OAC treatment and rates of ischemic and haemorrhagic stroke in a cohort of Norwegian patients with non-valvular AF aged ≥18 years with one non-sex CHA2DS2-VASc risk factor registered from 2011 to 2018, linking data from the Norwegian Population Registry, Patient Registry, Prescription Database and Cause of Death Registry. Individuals using OAC at baseline were excluded. Each individual had at least a three years look-back period for identification of their first non-sex CHA2DS2-VASc risk factor, after which they entered the study cohort and were followed until occurrence of stroke, death, emigration, higher CHA2DS2-VASc score or end of follow-up on December 31, 2018. Individuals were defined as exposed to OAC from the first redeemed prescription of OAC with a reimbursement code for AF and throughout follow-up. Rates of ischemic and haemorrhagic stroke were calculated as the number of stroke cases per 100 person-years, with 95% confidence intervals (CI).

Results

During 2011–2018, a total of 61,631 individuals with AF and intermediate risk of stroke were included (mean age 63,8±7,6 years (SD); 37% women), of whom 75% initiated OAC treatment. In total, 1709 ischemic strokes (405 cases in OAC users and 1304 in non-users) were registered during 214,738 person-years, and 378 haemorrhagic strokes (251 cases in OAC users and 127 in non-users) during 213,487 person-years. The rate of ischemic stroke was 0.39 (95% CI, 0.35–0.43) and 1.19 (95% CI, 1.12–1.25) per 100 person-years in OAC users and non-users, respectively. The haemorrhagic stroke rate was 0.24 (95% CI, 0.21–0-27) and 0.12 (95% CI, 0.10–0.14) per 100 person-years in OAC users and non-users, respectively. Both ischemic and haemorrhagic stroke rates were highest among those over 65 years of age (Figure 1).

Conclusion

In a nationwide cohort of Norwegian AF patients at intermediate risk of stroke, three out of four initiated treatment with OAC. Use of OAC was associated with a considerably lower rate of ischemic stroke compared to non-OAC use. Although haemorrhagic stroke rates were increased in the OAC-users vs. non-users, the hemorrhagic stroke rates were generally low.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Vestre Viken Health Trust Figure 1. Rates of ischemic and haemorrhagic stroke per 100 person-years in AF-patients at intermediate risk of stroke (CHA2DS2-VASc score 1 in men, score 2 in women) by OAC use during 2011 to 2018. Age corresponds to age at attainment of the first non-sex CHA2DS2-VASc risk factor.

Time trends in incidence rates of atrial fibrillation-related strokes in Norway 2001–2014: a nationwide analysis using data from the cardiovascular disease in Norway (CVDNOR) project

Background

Stroke incidence rates declined in Norway during 2001 to 2014. Atrial fibrillation (AF) incidence rates were stable in the same period.

Purpose

We aimed to study time trends in incidence (first time) of acute stroke hospitalizations and stroke deaths associated with AF in Norway in the period 2001–2014.

Methods

Nationwide hospital discharge diagnoses in the Cardiovascular Disease in Norway (CVDNOR) database and in the National Patient Registry were linked to the National Cause of Death Registry. All hospitalizations with acute stroke (including ischemic stroke, intracerebral bleeding and unspecified stroke) and out-of-hospital deaths with stroke as underlying cause in individuals 25 years and older were obtained during 1994–2014. Incident stroke was defined as the first hospitalization or out-of-hospital death due to stroke with no hospitalization for acute stroke or stroke sequela the past 7 years. Stroke was defined as AF-related if AF was registered during a hospitalization the past 7 years, or as underlying or contributing cause of death up to 28 days after the stroke hospitalization. Age-standardized incidence rates with 95% confidence intervals (CIs) were calculated using direct standardization to the age-distribution in the Norwegian population per 2001. Age-adjusted average yearly incidence rate ratios (IRR) with 95% CIs were estimated by negative binomial regression analyses.

Results

From 2001 to 2014 we identified 157 580 incident stroke cases of which 38 317 were AF-related. The proportion of incident strokes that were related to AF increased from 20.6% in 2001 to 26.3% in 2014. Age-standardized incidence rates of AF-related strokes per 100,000 person years were stable at 88 (85, 92) in 2001 and 79 (76, 83) in 2014, corresponding to a 0% average yearly change, IRR 1.00 (0.99, 1.00). The age-standardized incidence rates of non-AF-related strokes per 100,000 person years decreased from 334 (328, 341) in 2001 to 214 (209, 219) in 2014, corresponding to a 3% average yearly decrease, IRR 0.97 (0.97, 0.97).

Conclusion

The favourable trend in total stroke incidence rates from 2001 to 2014 does not include AF-related strokes. This may suggest that AF has become accountable for a higher proportion of incident strokes or that AF detection improved over this period.

Figure 1. Age-standardized incidence rates of stroke hospitalizations or out-of-hospital deaths per 100,000 person years (py) by year, illustrated as all strokes (blue horizontal line) and AF-related strokes (red horizontal line/height of red area). The height of the blue area illustrates the rate for non-AF related strokes.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Vestre Viken Hospital Trust (public hospital research fund)

Outbreak of encephalitic listeriosis in red-legged partridges (Alectoris rufa)

An outbreak of neurological disease was investigated in red-legged partridges between 8 and 28 days of age. Clinical signs included torticollis, head tilt and incoordination and over an initial eight day period approximately 30-40 fatalities occurred per day. No significant gross post mortem findings were detected. Histopathological examination of the brain and bacterial cultures followed by partial sequencing confirmed a diagnosis of encephalitis due to Listeria monocytogenes. Further isolates were obtained from follow-up carcasses, environmental samples and pooled tissue samples of newly imported day-old chicks prior to placement on farm. These isolates had the same antibiotic resistance pattern as the isolate of the initial post mortem submission and belonged to the same fluorescent amplified fragment length polymorphism (fAFLP) subtype. This suggested that the isolates were very closely related or identical and that the pathogen had entered the farm with the imported day-old chicks, resulting in disease manifestation in partridges between 8 and 28 days of age. Reports of outbreaks of encephalitic listeriosis in avian species are rare and this is to the best of our knowledge the first reported outbreak in red-legged partridges.

The effect of chlortetracycline treatment and its subsequent withdrawal on multi-resistant Salmonella enterica serovar Typhimurium DT104 and commensal Escherichia coli in the pig

AIMS

To investigate the effect of a therapeutic and sub-therapeutic chlortetracycline treatment on tetracycline-resistant Salmonella enterica serovar Typhimurium DT104 and on the commensal Escherichia coli in pig.

METHODS AND RESULTS

Salmonella Typhimurium DT104 was orally administered in all pigs prior to antibiotic treatment, and monitored with the native E. coli. Higher numbers of S. Typhimurium DT104 were shed from treated pigs than untreated pigs. This lasted up to 6 weeks post-treatment in the high-dose group. In this group, there was a 30% increase in E. coli with a chlortetracycline minimal inhibitory concentration (MIC) > 16 mg l-1 and a 10% increase in E. coli with an MIC > 50 mg l-1 during and 2 weeks post-treatment. This effect was less-pronounced in the low-dose group. PCR identified the predominant tetracycline resistance genes in the E. coli as tetA, tetB and tetC. The concentration of chlortetracycline in the pig faeces was measured by HPLC and levels reached 80 microg g-1 faeces during treatment.

CONCLUSION

Chlortetracycline treatment increases the proportion of resistant enteric bacteria beyond the current withdrawal time.

SIGNIFICANCE AND IMPACT OF THE STUDY

Treated pigs are more likely to enter abattoirs with higher levels of resistant bacteria than untreated pigs promoting the risk of these moving up the food chain and infecting man.

Evaluation of diarrhoea management of health professionals trained at the Diarrhoea Training Unit of Rawalpindi General Hospital

To promote the use of oral rehydration therapy (ORT), a training programme was launched by The Pakistan National Programme for Control of Diarrhoeal Disease (CDD) by establishing the Diarrhoea Training Units (DTUs). Physicians trained at DTU were designated to establish functioning oral rehydration therapy (ORT) corners at their health centres and train health workers in delivery of facilities on standard diarrhoea case management. The study was designed to evaluate the functioning of ORT corners three years after their establishment. The study revealed that ORT corners have failed to achieve the main objectives of DTU programme. Twenty-four out of 49 ORT corners were non-functional after three years of their establishment, mainly due to frequent transfers of trained staff. In 22 ORT corners evaluated, performance of health professionals was far from satisfactory, 19 out of 22 doctors were found to have inadequate performance in diarrhoea management and only 3 out of 7 LHVs performed adequately. LHVs could not consistently deliver health education messages to mothers. There seems to be a lack of interest and willingness to participate actively, as more than 50% of both doctors and LHVs did not consider ORT work as their job. We conclude that the ultimate objectives of improved and appropriate diarrhoea case management through ORT corners have not been achieved.

Mothers' perceptions of severe pneumonia in their own children: a controlled study in Pakistan

In 1992, 320 mothers were interviewed in a Rawalpindi hospital to identify which of the signs and symptoms they saw in their own children were most consistently linked with a clinical diagnosis of pneumonia as opposed to common cold. A related goal was to determine whether mothers could correctly judge the actual presence or absence of two major pneumonia signs--fast breathing and chest indrawing. The mothers were predominantly poor and 43% were illiterate. The study sample was composed of four matched groups: (1) mothers of 80 children with pneumonia, most with severe disease, interviewed after the child was referred to the ward; (2) mothers of 80 such children interviewed in the outpatient clinic prior to any discussion of the pneumonia diagnosis; (3) mothers of 80 children with common cold; and (4) mothers of 80 'well' children. Results showed that when mothers were interviewed in the clinic, their perception that a child had fast breathing and/or chest indrawing was highly correlated with pneumonia (sensitivity 64%, specificity 90%). Mothers were even more likely to say that a child had these signs after the pneumonia diagnosis had been conveyed, suggesting that interaction with doctors influenced their views. Fast breathing was better recognized than chest indrawing, and accurate diagnosis of both signs was better among mothers having prior experience with childhood pneumonia. The data suggest that even in the absence of formal ARI education, a majority of Pakistani mothers attending hospitals in indigent areas can recognize these two signs in their own children. However, the seriousness of the signs and their connection with pneumonia should be stressed in education campaigns since a high percentage of children had chest indrawing (a late sign of severe disease) by the time they were brought to the hospital.

Maternal perceptions of pneumonia and pneumonia signs in Pakistani children

Fifty mothers of children attending a hospital outpatient clinic with non-severe pneumonia (fast breathing but no chest indrawing) were interviewed in depth. Maternal perceptions and practices with clinical significance were documented. Results showed that most mothers initially tried "heat-producing" home remedies designed to counter the "coldness" of the disease, allowed only 2 days for any particular allopathic medicine to work, and did not go to the same practitioner twice. When mothers were asked what had alarmed them enough to come to the hospital, the symptoms named most frequently were persistent severe cough and high fever, inability to sleep and excessive crying. Fast breathing was spontaneously mentioned by only a few, although when questioned, 32/50 said that they had noticed it. The mothers who had prior experience with child pneumonia were more likely to notice fast breathing and also came to the hospital earlier than those who were inexperienced. Relatively higher levels of maternal education and income were suggestively associated with bringing a female child rather than a male child for pneumonia treatment. Fewer than half of the mothers knew where air goes when a person breathes in and where the lungs are located. Most held treatment preferences at odds with the protocols proposed for the national ARI program currently being initiated in Pakistan, e.g. they said that a doctor should use a stethoscope, should prescribe suspensions rather than tablets and should give injections. This study provides baseline data on attitudes and behaviors that can either be built on in that program or addressed through public education campaigns.