Screening for atrial fibrillation with the WatchBP device as compared to current clinical practice: a cost-analysis.

Transcription

1 Screening for atrial fibrillation with the WatchBP device as compared to current clinical practice: a cost-analysis. Introduction Atrial Fibrillation Atrial fibrillation (AF) is the most common cardiac arrhythmia. It affects over one percent of the general UK population and is related to one fifth of all strokes (European Heart Rhythm et al. 2010). For this reason it causes a major burden on healthcare: 0.62% of national healthcare expenditure in 1995 and increased to 0.97% in It is expected that the number of AF patients will increase by 40% in the coming two decades due to the ageing population and western lifestyle (Stewart, 2004). Many patients with AF have no symptoms (33%) and are not aware of its presence and therefore remain undiagnosed. If these patients suffering with AF could be diagnosed and treated at an early stage, the risk of stroke can be reduced by 68% (European Heart Rhythm et al., 2010). Current clinical practice According to the current Nice guidelines (NICE_CG36, 2011) AF should be screened opportunistically. This means that pulse palpation should be performed among patients presenting breathlessness/dyspnoea, palpitations, syncope/dizziness, chest discomfort or had a stroke/tia. Although many patients can be diagnosed with AF the method is not very accurate and requires an extra effort and extra costs ( 1.83 (Hobbs et al., 2005)). In addition, its accuracy can differ largely between studies (sensitivity ranging from % and specificity ranging from 69-81%) and observers (Morgan and Mant, 2002, Hobbs et al., 2005, Sudlow et al., 1998). The WatchBP device The WatchBP Home is an automated blood pressure monitor with an implemented AF detection system. When a GP or Patient measures blood pressure using the WatchBP, the device automatically screens for AF without any extra effort. As a simple explanation, the algorithm of the device calculates the irregularity index (SD divided by mean) based on interval times between heartbeats and if the irregularity index is above a certain threshold value a patient is diagnosed as having AF. If a patient performs self-measurements at home and the WatchBP Home detects AF, it gives a warning that a visit to the GP is required. The systems accuracy has been investigated in several scientific studies and showed high diagnostic accuracy (Stergiou et al. 2009; Wiesel et al. 2009). Although, the WatchBP device has never been directly compared to pulse palpation for AF screening, results from different clinical studies consistently show a higher diagnostic accuracy for the WatchBP (Stergiou et al. 2009; Wiesel et al. 2009) device than for pulse palpation as compared to the gold standard: a 12-lead ECG assessed by a consultant (Hobbs et al., 2005, Morgan and Mant, 2002, Somerville et al., 2000, Sudlow et al., 1998). Based on the results of the SAFE study the AF detector of the WatchBP monitor shows an even higher rate of accuracy for the detection of AF than a GP or nurse using a 12-lead ECG system (Hobbs et al. 2005) as compared to a 12- lead ECG assessment by a consultant. Patients without symptoms Pulse palpation is recommended for patients experiencing symptoms as described earlier. However, many people have no symptoms at all. Their numbers are estimated from one third (European Heart Rhythm et al., 2010) to the majority of AF patients (NICE_CG36, 2011). According to current guidelines these patients probably will remain undiagnosed, with a high risk of getting stroke in the future. With the WatchBP Home device patients can be screened for AF during blood pressure measurements without any extra effort. Since blood pressure is commonly measured on a routine basis during visits to the GP, asymptomatic patients who otherwise would not be screened for AF can be diagnosed with the WatchBP device. It is therefore estimated that with the WatchBP device more patients will be detected at an early stage so that treatment can be initiated earlier leading to an overall reduction in strokes. 1

2 ECG s If a doctor feels pulse irregularities an ECG should be performed for confirmation (NICE_CG36). Results from the SAFE study showed that this led to diagnosing a new AF patient in 17.5% (one of every 5.7 subjects) of all ECG screenings or 82.5% unnecessarily performed ECG s ( 16 (Hobbs et al., 2005)). Therefore, replacing pulse palpation by the WatchBP device might reduce the amount of unnecessary ECG s. The present cost-analysis report estimated the costs for AF screening and treatment when using the WatchBP device and compared this against pulse palpation; the current standard for AF screening. 2

3 Methods Strategies for Cost analyses For the cost calculation we compared AF screening by mean of pulse palpation against the WatchBP device. For the cost analysis the NICE costing report for the management of atrial fibrillation (NICE, 2006) was used as a platform, the costs for screening, treatment and adverse events were adopted and adjusted for inflation to 2011 figures. The first strategy follows the assumption that all new AF patients will be screened for AF, (patients with and without symptoms). Sensitivity analyse For cost analyses we varied the parameters for patients who would be considered for screening or not (patients with and without AF-related symptoms) and used different costs for stroke per patient per year. Symptoms Additional cost analyses were performed with the assumption that a part of all AF positive patients have no symptoms. It is estimated that 35% (European Heart Rhythm et al., 2010, NICE_CG36, 2011) to 50% (NICE_CG36, 2011) of all patients with AF have no symptoms. In accordance to the current recommended guidelines, these patients are not considered for pulse palpation. Under the assumption that these patients undergo routine blood pressure measurement during their visit at the GP s practice these patients undergo AF screening at the same time when blood pressure is measured with the WatchBP device. Accuracy of the screening methods For the reliability of pulse palpation we verified 4 studies (Morgan and Mant, 2002, Somerville et al., 2000, Sudlow et al., 1998, Hobbs et al., 2005). We excluded two studies because pulse palpation was not compared to a 12-lead ECG (Sudlow et al., 1998) or the study was carried out at only one GP s practice and therefore may not be representative for overall healthcare (Somerville et al., 2000). As a consequence the calculations were performed with the results obtained from the studies of Morgan (91% sensitivity, 74% specificity) and Hobbs (87.2% sensitivity, 81.3% specificity). For the accuracy of the WatchBP device with AF detection system we used the results of studies from Wiesel (97% sensitivity and 89% specificity) and Stergiou (100% sensitivity and 89% specificity) (Wiesel et al., 2009, Stergiou et al., 2009). For cost calculation the average cost based on the results of the studies of Hobbs and Morgan were compared to the average costs based on the results of the studies of Wiesel and Stergiou AF incidence of the GP population For the estimation of the UK incidence we followed the example from the NICE costing report of 2006 (NICE, 2006) and used the annual incidence of 0.175% which equalizes 87,000 new cases per year. Based on the sensitivity and specificity results of the SAFE-trial for pulse palpation and the additional finding that in 1 out of every 5.7 patients with irregular pulse, AF presence is confirmed by 12-lead ECG, we calculated that this number would be found with an AF incidence of 4.4% using the following formula: (incidence x sensitivity) / ((incidence x sensitivity + (1-incidence)) x (1-specificity)). This incidence is higher than the general AF incidence but we estimate that this is representative for the population that is screened for AF (high risk, symptoms) as these are commonly elder people with certain risk factors. Costs assumptions For the cost analysis the NICE costing report for the management of atrial fibrillation (NICE, 2006) was used as a platform, which means that the costs for screening and treatment were adopted and adjusted for inflation to 2011 figures. The inflation was estimated at 5% per year. This was similar to the NICE costing report using a HCSC inflation rate of 27% to adjust prices from 2001 to 2006 (NICE_CG36, 2011). 3

4 Table A, costs for treatment from the NICE costing report 2006 and adjusted for inflation to 2011 Costs ECG Palpitations Anti-Coagulants Stroke Major Bleeds Minor Bleeds Costs for stroke In the NICE costing report the annual average cost for stroke was estimated at 7,800, which was used for the current de novo cost-analysis with adjustment for 2011 ( 9,906). However, as more studies estimated the costs for stroke an extra analysis was performed using the estimated costs of 44k per patient as the annual costs for stroke (Saka et al., 2009) ( In addition, it was calculated at what costs for stroke the costs for screening would be offset due to number of stroke (costs) prevented. Proportions of patients treated and adverse events Further, we adopted the proportion assumptions from the NICE costing report. We followed the proposal that 56% of detected AF patients should use anticoagulants (A-C), 32% of all patients use aspirin. The percentage of stroke annually prevented by Warfarin was estimated at 4.3% and for aspirin this was estimated 0.9%. The percentage of adverse events was estimated at 2.4% for major bleeds and 15.8% for minor bleeds for those patients using anti-coagulation. Costs for pulse palpation The cost of pulse palpation were estimated at 1.83 as obtained from the SAFE-trial (Hobbs et al., 2005). For the detection with the WatchBP device we calculated no costs as it was assumed that blood pressure measurement is performed among these patients when visiting a GP. 4

5 Results Cost effectiveness analysis I The first example of the cost effectiveness analysis assumes that all new AF incidences will be screened for AF This analysis is rather similar to the NICE costing report with the exception that the number of false positives has been taken into account. Based on the accuracy of pulse palpation (Morgan, Hobbs) it is estimated that from the 87,000 new AF cases each year 7,830 (Morgan) or 11,180 (Hobbs) are not detected (False Negatives). See table I in the appendix. Based on the finding that a stroke cost 9,906 per patient per year, both screening methods cost money. Due to the higher sensitivity of the WatchBP device more AF patients will be diagnosed than with pulse palpation (85,695 vs. 77,495 patients) leading to higher costs for treatment ( 23.3M vs. 21.1M) and adverse events related to anti-coagulation drugs ( 3.2M vs. 3.1M) but more cost savings due to a higher number of stroke prevention ( 22.9M vs. 20.7M). The higher specificity of the WatchBP device leads to a lower number of patients falsely diagnosed as AF positive (207,930 vs. 422,381) and therefore a reduction in the number of ECGs (293,625 vs. 499,877) and related costs for ECG assessment( 10.5M vs. 18.0M). The overall cost for screening with pulse palpation is further increased by the costs for palpation ( 4.6M) where screening with the WatchBP does not require extra costs. See Table 1a. Overall the WatchBP device will save approx. 11.6M as compared to pulse palpation based on the average pulse palpation costs (Morgan and Hobbs) minus the average WatchBP costs (Wiesel, Stergiou). In addition, it is estimated that screening with the WatchBP device will prevent 221 (11%) more strokes than by pulse palpation. See Table 1b Table1a, costs for screening and treatment, when all patients would be considered for atrial fibrillation screening Costs AC Major Bleeds Minor Bleeds Palpitations ECG's Strokes prevented Total costs Wiesel (WatchBP) Stergiou (WatchBP) Morgan (PP) Hobbs (PP) AC, indicates anti-coagulants; pp, pulse palpation Table 1b, Strokes prevented and overall costs for atrial fibrillation screening and treatment Strokes prevented Studies (n) Wiesel (WatchBP) 2275 Stergiou (WatchBP) 2346 Morgan (PP) 2134 Hobbs (PP) 2044 PP indicates pulse palpation See also Table I in the appendix for more detailed information. 5

6 Cost effectiveness analysis II Extra The second example is based on the assumption that a part of all AF positive patients have no symptoms. Patients without symptoms are likely to be detected by the WatchBP device during routine blood pressure measurement, whereas they would remain undiagnosed by pulse palpation because there would be no indication for screening. IIa If from all new AF positive patients 35% have no symptoms then (87,000*65%) 56,550 patients would be considered for pulse palpitation. With the WatchBP device all patients would be screened for AF under the assumption that their blood pressure is routinely measured during a visit at the GP. Despite the fact that with the WatchBP more patients will be diagnosed with WatchBP than with pulse palpation and thus treatment costs, costs for adverse events, screening costs and ECG assessment costs are increased, the overall AF screening and treatment costs are approx. 2.6M lower (Table 2a.a) due to cost savings related to a higher number of strokes (952) prevented (Table 2a.b). Table2a.a, costs for screening and treatment when 35% of all new atrial fibrillation patients are without symptoms Costs AC Major Bleeds Minor Bleeds Palpitations ECG's Strokes prevented Total costs Wiesel (WatchBP) Stergiou (WatchBP) Morgan (PP) Hobbs (PP) Table 2a.b, strokes prevented when 35% of all new atrial fibrillation patients are without symptoms Strokes prevented Studies (n) Wiesel (WatchBP) 2275 Stergiou (WatchBP) 2346 Morgan (PP) 1387 Hobbs (PP) 1329 PP indicates pulse palpation IIB If from all new AF positive patients 50% would be without any symptoms then screening with the WatchBP device would lead to 1.2M higher costs on average (Table 2b.a) and 1266 more strokes being prevented on average (Table 2b.b) as compared to pulse palpation. The lower costs for pulse palpation are mainly due to the fact that less ECG s are performed and fewer patients are treated with Warfarin. See Table IIb in the appendix for the detailed overview. Table2b.a, costs for screening and treatment when 50% of all new atrial fibrillation patients are without symptoms Costs AC Major Bleeds Minor Bleeds Palpitations ECG's Strokes prevented Total costs Wiesel (WatchBP) Stergiou (WatchBP) Morgan (PP) Hobbs (PP)

7 Table 2b.b, strokes prevented when 50% of all new atrial fibrillation patients are without symptoms Strokes prevented Studies (n) Wiesel (WatchBP) 2275 Stergiou (WatchBP) 2346 Morgan (PP) 1067 Hobbs (PP) 1022 See also Tables IIA and B in the appendix for more detailed information. 7

8 Cost effectiveness analysis III III Costs for stroke The above cost analyses took into account 9,906 as the annual costs for stroke. However, it is indicated that the annual costs for stroke may be higher. For this reason we performed the same analysis again when using 44,000 per patient as the annual costs for stroke (Saka et al., 2009) ( Since changing in costs has no consequences for the number of strokes prevented only the costs are provided in below examples IIIa If 87,000 new AF patients are considered for screening with the WatchBP device and pulse palpation, both screening methods show the average cost savings for healthcare of 64.6M and 45.4M on average for WatchBP and pulse palpation, respectively (See Table 3a). Table3a, costs for screening and treatment, when all patients would be considered for atrial fibrillation screening and cost for stroke is 44,000 per patient per annum Anticoagulants Major Bleeds Minor Bleeds Palpitations ECG's Strokes prevented Total Costs costs Wiesel (WatchBP) Stergiou (WatchBP) Morgan (PP) Hobbs (PP) IIIb If 35% of all new AF patients are without symptoms this would mean that the number of strokes that are prevented by screening with pulse palpation will reduce to 1358 together with related cost savings for healthcare to 29.4M on average, whereas for WatchBP both stroke prevention and related cost-savings remain similar as (See Table IIIb in the Appendix). Table3b, costs for screening and treatment when 35% of all new atrial fibrillation patients are without symptoms and cost for stroke is 44,000 per patient per annum Anticoagulants Major Bleeds Minor Bleeds Palpitations ECG's Strokes prevented Total Costs costs Wiesel (WatchBP) Stergiou (WatchBP) Morgan (PP) Hobbs (PP) IIIc When 50% of all new AF patients are without symptoms the number of strokes prevented and related costssavings for pulse palpation will diminish further as compared to WatchBP, leading to 1045 strokes prevented and 22.7M cost-saving for pulse palpation. The number of strokes prevented and related cost-saving for WatchBP remain unchained (See Table IIIc in the Appendix). Table3c, costs for screening and treatment when 35% of all new atrial fibrillation patients are without symptoms and cost for stroke is 44,000 per patient per annum Anticoagulants Major Bleeds Minor Bleeds Palpitations ECG's Strokes prevented Total Costs costs Wiesel (WatchBP) Stergiou (WatchBP) Morgan (PP) Hobbs (PP) See also Tables IIIA, B and C in the appendix for more detailed information. 8

9 Break-even point Since there are some uncertainties about the annual cost for stroke we decided to calculate at which point screening for AF would be cost effective using the fact that the cost savings for stroke prevention offsets the cost of screening. The so called break-even costs for stroke were 16,090, 15,990 for Wiesel and Stergiou (WatchBP) and and for Morgan and Hobbs (PP), respectively (Figure 1). This was calculated with the assumption that all new AF cases (87.000) were considered for pulse palpation. When assuming that some new AF patients are without symptoms and thus are not considered for pulse palpation, the break-even cost for stroke would be lower for pulse palpation but not for WatchBP. 9

10 Total costs screening and treatment 50,000,000 40,000,000 30,000,000 20,000,000 10,000, ,000,000-20,000,000-30,000,000-40,000,000 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 18,000 20,000 22,000 24,000 26,000 28,000 Wiesel (WatchBP) 32,054,92 27,504,61 22,954,30 18,403,99 13,853,68 9,303,380 4,753, ,762-4,347,54-8,897,85-13,448,1-17,998,4-22,548,7-27,099,0 Stergiou (WatchBP) 32,960,55 28,123,57 23,432,53 18,741,49 14,050,45 9,359,412 4,668,372-22,668-4,713,70-9,404,74-14,095,7-18,786,8-23,477,8-28,168,9 Morgan (PP) 45,346,87 41,078,03 36,809,18 32,540,34 28,271,49 24,002,64 19,733,80 15,464,95 11,196,10 6,927,262 2,658,415-1,610,43-5,879,27-10,148,1 Hobbs (PP) 39,393,37 35,305,13 31,216,89 27,128,65 23,040,40 18,952,16 14,863,92 10,775,68 6,687,443 2,599,202-1,489,04-5,577,28-9,665,52-13,753,7 Figure 1, relationship between total costs for screening and treatment of atrial fibrillation (y-ax) and costs for stroke per patient per annum (x-ax) 10

11 Discussion As compared to pulse palpation screening for AF with the WatchBP device will lead to approx. 45% cost-savings ( 12M) and 11% reduction in the number of strokes (221 strokes). As screening with the WatchBP leads to a lower number of false negatives more patients will be treated for AF, which leads to higher costs for anticoagulant drugs and related adverse events (major and minor bleeds). On the other hand, screening with the WatchBP device leads to a lower number of false positives so that less 12-lead ECG s for confirmation are required. When screening for AF with the WatchBP device it is estimated that for the detection of one new AF case 3.4 ECG s are required. This means a reduction with more than 2 unnecessary ECG s per newly diagnosed AF patient as compared to pulse palpation based on the results of the SAFE-trial (Hobbs et al., 2005). In the above findings it has been taken into account that all new AF cases are screened for AF by both methods. However, approx 35 to 50% of all AF patients do not experience any symptoms related to the disease. In practice this would mean that these patients would not be considered for pulse palpation. It is estimated that this would lead to a higher difference between screening methods in the number of newly diagnosed AF patients since symptomless AF patients can be detected with the WatchBP device when blood pressure measurement is routinely performed at the GP s visit. This would lead to a higher difference between both methods in the number of strokes prevented and also leads to higher costs for treatment. What would be the consequences for overall healthcare costs depends on what would be the exact costs for stroke per patient per annum is. 12-lead ECG When finding an AF positive patient with the WatchBP device it is then recommended that a 12-lead ECG is assessed for confirmation. However, it should be realized that, according to the results of the SAFE trial a 12- lead ECG assessed by a GP does not seem to show higher accuracy for diagnosing AF than the WatchBP device as compared to 12-lead ECG assessment by a consultant (Hobbs et al., 2005, Wiesel et al., 2009, Stergiou et al., 2009). The chance of a false negative result is higher for the ECG assessed by a GP or nurse than for the WatchBP device. Therefore, instead of performing a 12-lead ECG in the physicians office one could also consider performing extra measurements in the GP s practice with the WatchBP device or give the WatchBP Home A to a patient to take multiple measurements at home. As screening with the WatchBP is cheaper in both measurement and device, this would decrease costs for AF screening even further. For this it must be taken into account that the ECG also can diagnose other arrhytmia s or cardiac diseases, which cannot be done with the WatchBP device. Therefore the ECG device cannot be totally replaced by the WatchBP devicein the GP s practice. Finally, it should be mentioned that clinical studies to the WatchBP device showed that among the patients, who were diagnosed as false positive, a part of them had other arrhythmia s and therefore the confirming ECG s may not all be classified as unnecessary. Paroxysmal Atrial fibrillation Outside the use in the GP s practice the WatchBP Home A device can also be given to patients suspected of having paroxysmal AF to take measurements at home. In practice this means that the device can be given instead of a 24-h ambulatory device. When the WatchBP Home A would be used by patients who have paroxysmal AF without symptoms this may reduce costs for overall healthcare as the WatchBP Home A device is cheaper than the average ambulatory ECG device. Patients with hypertension are at increased risk of having (paroxysmal) AF. Due to their hypertension these patients may have purchased a blood pressure device themselves for performing self-measurement of blood pressure at home. If these patients would purchase the WatchBP Home A which is at a similar price range as most validated home blood pressure monitors are, they may detect the presence of paroxysmal AF which is mostly asymptomatic (Lip et al., 2008). Since patients with paroxysmal AF have a similar stroke risk as patients with permanent AF (Friberg et al., 2010) this could also help to prevent the occurrence of stroke in the future. 11

12 The cost savings for paroxysmal AF have not been taken into account for the present cost analysis, because the incidence and prevalence is difficult to estimate. In addition, it cannot be estimated how many patients would purchase the WatchBP Home A device for performing self-measurement of blood pressure at home. If the WatchBP devices are implemented in general clinical practice it may help to improve the insight into the incidence and prevalence of paroxysmal AF in the UK. In addition, when the WatchBP home A is used for patients at home for regular blood pressure monitoring it could also lead to better blood pressure control as patients are more aware of their blood pressure, which can lead to improved lifestyle and better adherence to treatment. In addition, the implemented schedule for self-measurement of blood pressure at home helps patients to obtain a reliable estimate of a patient s true blood pressure value. In fact it may give a more reliable estimate of a patients blood pressure value that could reduce unnecessary treatment of hypertension and improve blood pressure control (Verberk et al., 2005, Verberk et al., 2007) At the present cost-analysis the price of the monitor has not been taken into account as it is assumed that GP s need to have a blood pressure monitor anyway. However, when considered that the WatchBP Home A device costs approximately 75 per device and is used for an average period of three years, the annual costs will be 25 per device per year. Assuming that the total screening will be covered by GP the costs of the devices will be 1M extra per year. If GP s would prefer to use a professional blood pressure monitor with AF detector, a device that is more sophisticated with extra possibilities and will cost approx 500. Assuming that this device will be used 5 years on average, the annual costs are estimated at 100 which will be 4M extra costs for the device per year. Current NICE guidelines state that everyone with an irregular pulse should be given an ECG the average cost of performing this function is approx 30 of which only 1 in 5 are found to have AF. The WatchBP device would cut down the need for an ECG by some 40% thus reducing hospital waiting times and overall healthcare costs. Conclusion The WatchBP device can help improving AF screening in regular clinical practice, without any extra efforts. It is less liable to observer bias than pulse palpation. When the WatchBP device is used for routine blood pressure measurement in the GP s practice, it will also diagnose AF positive patients without AF-related symptoms, a group that remain undetected when screened by pulse palpation. It is expected to lead to a lower number of unnecessary ECG s for confirmation of AF presence. The higher number of patients detected with AF by the WatchBP device as compared to pulse palpation would lead to higher costs for treatment and related adverse events, which are (partly) offset by the cost savings due to increased stroke prevention. The WatchBP Home A device can help detect paroxysmal atrial fibrillation. As the WatchBP Home A device is not more expensive than other validated blood pressure monitors, paroxysmal AF might also be widely detected by consumers who measure their blood pressure at home and would otherwise not visit their GP. 12

13 References EUROPEAN HEART RHYTHM, A., EUROPEAN ASSOCIATION FOR CARDIO-THORACIC, S., CAMM, A. J., KIRCHHOF, P., LIP, G. Y., SCHOTTEN, U., SAVELIEVA, I., ERNST, S., VAN GELDER, I. C., AL-ATTAR, N., HINDRICKS, G., PRENDERGAST, B., HEIDBUCHEL, H., ALFIERI, O., ANGELINI, A., ATAR, D., COLONNA, P., DE CATERINA, R., DE SUTTER, J., GOETTE, A., GORENEK, B., HELDAL, M., HOHLOSER, S. H., KOLH, P., LE HEUZEY, J. Y., PONIKOWSKI, P., RUTTEN, F. H., GUIDELINES, E. S. C. C. F. P., VAHANIAN, A., AURICCHIO, A., BAX, J., CECONI, C., DEAN, V., FILIPPATOS, G., FUNCK-BRENTANO, C., HOBBS, R., KEARNEY, P., MCDONAGH, T., POPESCU, B. A., REINER, Z., SECHTEM, U., SIRNES, P. A., TENDERA, M., VARDAS, P. E., WIDIMSKY, P., DOCUMENT, R., AGLADZE, V., ALIOT, E., BALABANSKI, T., BLOMSTROM-LUNDQVIST, C., CAPUCCI, A., CRIJNS, H., DAHLOF, B., FOLLIGUET, T., GLIKSON, M., GOETHALS, M., GULBA, D. C., HO, S. Y., KLAUTZ, R. J., KOSE, S., MCMURRAY, J., PERRONE FILARDI, P., RAATIKAINEN, P., SALVADOR, M. J., SCHALIJ, M. J., SHPEKTOR, A., SOUSA, J., STEPINSKA, J., UUETOA, H., ZAMORANO, J. L. & ZUPAN, I. (2010) Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Europace, 12, FRIBERG, L., HAMMAR, N. & ROSENQVIST, M. (2010) Stroke in paroxysmal atrial fibrillation: report from the Stockholm Cohort of Atrial Fibrillation. Eur Heart J, 31, HOBBS, F. D., FITZMAURICE, D. A., MANT, J., MURRAY, E., JOWETT, S., BRYAN, S., RAFTERY, J., DAVIES, M. & LIP, G. (2005) A randomised controlled trial and cost-effectiveness study of systematic screening (targeted and total population screening) versus routine practice for the detection of atrial fibrillation in people aged 65 and over. The SAFE study. Health Technol Assess, 9, iii-iv, ix-x, LIP, G. Y., FRISON, L. & GRIND, M. (2008) Stroke event rates in anticoagulated patients with paroxysmal atrial fibrillation. J Intern Med, 264, MORGAN, S. & MANT, D. (2002) Randomised trial of two approaches to screening for atrial fibrillation in UK general practice. Br J Gen Pract, 52, 373-4, NICE (2006) CG36 Atrial fibrillation: Cost impact report. NICE_CG36 (2011) Atrial Fibrillation. National clinical guideline for management in primary and secondary care SAKA, O., MCGUIRE, A. & WOLFE, C. (2009) Cost of stroke in the United Kingdom. Age Ageing, 38, SOMERVILLE, S., SOMERVILLE, J., CROFT, P. & LEWIS, M. (2000) Atrial fibrillation: a comparison of methods to identify cases in general practice. Br J Gen Pract, 50, STERGIOU, G. S., KARPETTAS, N., PROTOGEROU, A., NASOTHIMIOU, E. G. & KYRIAKIDIS, M. (2009) Diagnostic accuracy of a home blood pressure monitor to detect atrial fibrillation. J Hum Hypertens, 23, STEWART, S. (2004) Epidemiology and economic impact of atrial fibrillation. J Cardiovasc Nurs, 19, SUDLOW, M., RODGERS, H., KENNY, R. A. & THOMSON, R. (1998) Identification of patients with atrial fibrillation in general practice: a study of screening methods. Bmj, 317,

14 VERBERK, W. J., KROON, A. A., KESSELS, A. G. & DE LEEUW, P. W. (2005) Home blood pressure measurement a systematic review. J Am Coll Cardiol, 46, VERBERK, W. J., KROON, A. A., LENDERS, J. W., KESSELS, A. G., VAN MONTFRANS, G. A., SMIT, A. J., VAN DER KUY, P. H., NELEMANS, P. J., RENNENBERG, R. J., GROBBEE, D. E., BELTMAN, F. W., JOORE, M. A., BRUNENBERG, D. E., DIRKSEN, C., THIEN, T. & DE LEEUW, P. W. (2007) Self-measurement of blood pressure at home reduces the need for antihypertensive drugs: a randomized, controlled trial. Hypertension, 50, WIESEL, J., FITZIG, L., HERSCHMAN, Y. & MESSINEO, F. C. (2009) Detection of atrial fibrillation using a modified microlife blood pressure monitor. Am J Hypertens, 22,