Baylor University Medical Center Proceedings July 2017 - 283

factors associated with AF varied across studies, and we noted
that not all risk factors were considered in these studies. Overall,
AF was found to be higher among those with advanced age (19-
22, 24-26, 28-30), male gender (19-22, 30), hypertension (19,
21, 24, 28, 31), diabetes (19, 24, 28), prior myocardial infarction
(16, 21, 26, 28, 30), prior stroke (21, 24, 29), obesity (26, 29),
hyperlipidemia/hypercholesterolemia (19, 29, 30), alcohol consumption (16, 26, 28), and heart failure (24). Furthermore, ECG
and echocardiographic ﬁndings of left ventricular hypertrophy
(22, 26, 28, 30), low left ventricular ejection fraction (28), left
bundle branch block (16), left atrial diameter (30), peak early
rapid ﬁlling wave velocity (30), myocardial ischemia (21), and
ventricular premature beats (21) were found to be associated with
AF. Only six studies (19, 24, 26, 28-30) performed univariate
and multivariate analyses to establish signiﬁcant disease associations, while the rest reported descriptive statistics.
DISCUSSION
To our knowledge, this is the ﬁrst systematic review on global
rural AF screening and risk factors. We found that the global
pooled prevalence of AF in rural areas was 2.05% based on the
18 articles that we reviewed. This overall prevalence rate is comparable with ﬁndings from earlier systematic reviews using four
large population-based surveys (2.3%) (33) and another with
30 studies across urban or mixed urban-rural settings (2.2%)
(34); conversely, our pooled AF rate is relatively lower than that
observed in large urban screening studies (2, 12). In the three articles with mixed urban and rural participants, one study showed
that AF burden was higher among urban residents (26), while the
reverse was observed in the other two studies (23, 29). However,
the sampling methods and sample size in these studies were
modest, with a population range of 1,418 to 19,363.
AF risk factors were reported variably across studies. We
noted signiﬁcant associations between rural AF and increasing
age (19-22, 24-26, 28-30). Male gender (19-22, 30), hypertension (19, 21, 24, 28, 31), diabetes (19, 24, 28), prior myocardial
ischemia/infarction (16, 21, 26, 28, 30), alcohol consumption
(16, 26, 28), prior stroke (21, 24, 29), and obesity (26, 29) were
also associated with AF. What is apparent from our review is that
none of the studies reported all the risk factors or comorbidities
that may be associated with AF. Moreover, we noted from our
review that while middle age was considered in rural screening
in 22% of studies, risk factors such as obesity and hypertension
were not always considered in determining associated risk factors
for AF (35). Furthermore, the years in which our studies were
conducted ranged from 1965 to 2016; thus, it is possible that
over time, there could have been changes in lifestyle risk factors
that could predispose rural populations to develop AF. On the
other hand, the Framingham Heart Study, for example, noted
that while the prevalence of most cardiac risk factors changes over
a span of 50 years, their associated hazards for AF changed little
(36). Our study does not allow us to comment on longitudinal
changes in risk factors over time, since none of the reviewed studies' populations had follow up over a prolonged period of time.
There is a well-known increase in the prevalence and incidence of AF with advancing age (≥60 years old). Another sigJuly 2017

niﬁcant risk factor is male gender. Both aging and male gender
were similarly observed in the Framingham Heart Study (8) and
the Rotterdam Study (2). Moreover, the Framingham Study
also reported hypertension, diabetes, and myocardial infarction
as independent predictors of AF (8). Advancing age and male
gender would theoretically increase the risk for AF regardless
of rural or urban areas since age and sex are nonmodiﬁable
demographic risk factors consistently reported in studies.
Participants across studies were recruited based on age cutoﬀs, with the lowest cut-oﬀ being 16 years old and the highest
70 years old. This could partly explain the variance in prevalence
rates across studies. While the overall prevalence of AF in the
general population studies is 0.95%, aging plays a role, with
rates ranging from 0.1% among adults <55 years old to 9.0%
in those >80 years (37). Hence, a lower age cut-oﬀ likely results
in a lower AF prevalence rate. However, other factors may aﬀect
AF occurrence in the population, as observed in Tanzania, where
even though the participants were ≥70 years old, the prevalence
of AF was only 0.67% (25). The authors suggested that low AF
prevalence may be due to a lower body mass index among participants, a lower incidence of ischemic heart disease, or earlier
mortality for those who developed AF (25). Ethnic background
may inﬂuence AF burden. For example, the African American
AF paradox has been observed, where there is a lower prevalence
and incidence of AF in African Americans despite a higher
prevalence of AF risk factors compared to Caucasians (38).
We noted in our analysis an inconsistent association of alcohol consumption with AF. An increase in AF risk for regular
alcohol usage or higher rates of alcohol intake was noted (16,
26, 28). However, one study found that not consuming alcohol
was a signiﬁcant predictor of AF (21). Previous studies have
documented the cardiovascular beneﬁts of low to moderate alcohol intake (39); however, heavy drinking has also been shown
to be a strong risk factor for the development of AF (40-42).
The variation in associations may be due to the diﬀerences in
alcohol consumption patterns between rural and urban areas
and across diﬀerent countries and the type of alcohol consumed.
For example, Australian rural and regional areas tend to have
higher rates of alcohol use compared to urban areas (43, 44),
whereas in America, urban locales have higher alcohol consumption patterns (45).
In a small number of studies, we noted the use of primary
hospital admissions data or electronic medical records (1, 46,
47). Due to the high cost of conducting population-based
screening studies (48), administrative and medical records may
be an alternative source to establish AF prevalence in certain
populations. A few studies also focused on chronic conditions,
such as hypertension (49), stroke (50, 51), and hypertrophic
cardiomyopathy (52). Because these preexisting comorbid conditions are associated with a higher burden of AF, these studies
were excluded from prevalence calculations.
Most studies we reviewed used a 12-lead ECG to detect AF;
only the Chinese Longitudinal Healthy Longevity Survey (29)
used a single-lead ECG device. A 12-lead ECG remains the gold
standard for AF screening (53). Newer ECG devices (54-58)
for arrhythmia detection and analysis have become available.

Review of screening studies for atrial fibrillation in rural populations of 11 countries

283

Table of Contents for the Digital Edition of Baylor University Medical Center Proceedings July 2017

No label
Baylor University Medical Center Proceedings July 2017 - No label
Baylor University Medical Center Proceedings July 2017 - Cover2
Baylor University Medical Center Proceedings July 2017 - 253
Baylor University Medical Center Proceedings July 2017 - 254
Baylor University Medical Center Proceedings July 2017 - 255
Baylor University Medical Center Proceedings July 2017 - 256
Baylor University Medical Center Proceedings July 2017 - 257
Baylor University Medical Center Proceedings July 2017 - 258
Baylor University Medical Center Proceedings July 2017 - 259
Baylor University Medical Center Proceedings July 2017 - 260
Baylor University Medical Center Proceedings July 2017 - 261
Baylor University Medical Center Proceedings July 2017 - 262
Baylor University Medical Center Proceedings July 2017 - 263
Baylor University Medical Center Proceedings July 2017 - 264
Baylor University Medical Center Proceedings July 2017 - 265
Baylor University Medical Center Proceedings July 2017 - 266
Baylor University Medical Center Proceedings July 2017 - 267
Baylor University Medical Center Proceedings July 2017 - 268
Baylor University Medical Center Proceedings July 2017 - 269
Baylor University Medical Center Proceedings July 2017 - 270
Baylor University Medical Center Proceedings July 2017 - 271
Baylor University Medical Center Proceedings July 2017 - 272
Baylor University Medical Center Proceedings July 2017 - 273
Baylor University Medical Center Proceedings July 2017 - 274
Baylor University Medical Center Proceedings July 2017 - 275
Baylor University Medical Center Proceedings July 2017 - 276
Baylor University Medical Center Proceedings July 2017 - 277
Baylor University Medical Center Proceedings July 2017 - 278
Baylor University Medical Center Proceedings July 2017 - 279
Baylor University Medical Center Proceedings July 2017 - 280
Baylor University Medical Center Proceedings July 2017 - 281
Baylor University Medical Center Proceedings July 2017 - 282
Baylor University Medical Center Proceedings July 2017 - 283
Baylor University Medical Center Proceedings July 2017 - 284
Baylor University Medical Center Proceedings July 2017 - 285
Baylor University Medical Center Proceedings July 2017 - 286
Baylor University Medical Center Proceedings July 2017 - 287
Baylor University Medical Center Proceedings July 2017 - 288
Baylor University Medical Center Proceedings July 2017 - 289
Baylor University Medical Center Proceedings July 2017 - 290
Baylor University Medical Center Proceedings July 2017 - 291
Baylor University Medical Center Proceedings July 2017 - 292
Baylor University Medical Center Proceedings July 2017 - 293
Baylor University Medical Center Proceedings July 2017 - 294
Baylor University Medical Center Proceedings July 2017 - 295
Baylor University Medical Center Proceedings July 2017 - 296
Baylor University Medical Center Proceedings July 2017 - 297
Baylor University Medical Center Proceedings July 2017 - 298
Baylor University Medical Center Proceedings July 2017 - 299
Baylor University Medical Center Proceedings July 2017 - 300
Baylor University Medical Center Proceedings July 2017 - 301
Baylor University Medical Center Proceedings July 2017 - 302
Baylor University Medical Center Proceedings July 2017 - 303
Baylor University Medical Center Proceedings July 2017 - 304
Baylor University Medical Center Proceedings July 2017 - 305
Baylor University Medical Center Proceedings July 2017 - 306
Baylor University Medical Center Proceedings July 2017 - 307
Baylor University Medical Center Proceedings July 2017 - 308
Baylor University Medical Center Proceedings July 2017 - 309
Baylor University Medical Center Proceedings July 2017 - 310
Baylor University Medical Center Proceedings July 2017 - 311
Baylor University Medical Center Proceedings July 2017 - 312
Baylor University Medical Center Proceedings July 2017 - 313
Baylor University Medical Center Proceedings July 2017 - 314
Baylor University Medical Center Proceedings July 2017 - 315
Baylor University Medical Center Proceedings July 2017 - 316
Baylor University Medical Center Proceedings July 2017 - 317
Baylor University Medical Center Proceedings July 2017 - 318
Baylor University Medical Center Proceedings July 2017 - 319
Baylor University Medical Center Proceedings July 2017 - 320
Baylor University Medical Center Proceedings July 2017 - 321
Baylor University Medical Center Proceedings July 2017 - 322
Baylor University Medical Center Proceedings July 2017 - 323
Baylor University Medical Center Proceedings July 2017 - 324
Baylor University Medical Center Proceedings July 2017 - 325
Baylor University Medical Center Proceedings July 2017 - 326
Baylor University Medical Center Proceedings July 2017 - 327
Baylor University Medical Center Proceedings July 2017 - 328
Baylor University Medical Center Proceedings July 2017 - 329
Baylor University Medical Center Proceedings July 2017 - 330
Baylor University Medical Center Proceedings July 2017 - 331
Baylor University Medical Center Proceedings July 2017 - 332
Baylor University Medical Center Proceedings July 2017 - 333
Baylor University Medical Center Proceedings July 2017 - 334
Baylor University Medical Center Proceedings July 2017 - 335
Baylor University Medical Center Proceedings July 2017 - 336
Baylor University Medical Center Proceedings July 2017 - 337
Baylor University Medical Center Proceedings July 2017 - 338
Baylor University Medical Center Proceedings July 2017 - 339
Baylor University Medical Center Proceedings July 2017 - 340
Baylor University Medical Center Proceedings July 2017 - 341
Baylor University Medical Center Proceedings July 2017 - 342
Baylor University Medical Center Proceedings July 2017 - 343
Baylor University Medical Center Proceedings July 2017 - 344
Baylor University Medical Center Proceedings July 2017 - 345
Baylor University Medical Center Proceedings July 2017 - 346
Baylor University Medical Center Proceedings July 2017 - 347
Baylor University Medical Center Proceedings July 2017 - 348
Baylor University Medical Center Proceedings July 2017 - 349
Baylor University Medical Center Proceedings July 2017 - 350
Baylor University Medical Center Proceedings July 2017 - 351
Baylor University Medical Center Proceedings July 2017 - 352
Baylor University Medical Center Proceedings July 2017 - 353
Baylor University Medical Center Proceedings July 2017 - 354
Baylor University Medical Center Proceedings July 2017 - 355
Baylor University Medical Center Proceedings July 2017 - 356
Baylor University Medical Center Proceedings July 2017 - 357
Baylor University Medical Center Proceedings July 2017 - 358
Baylor University Medical Center Proceedings July 2017 - 359
Baylor University Medical Center Proceedings July 2017 - 360
Baylor University Medical Center Proceedings July 2017 - 361
Baylor University Medical Center Proceedings July 2017 - 362
Baylor University Medical Center Proceedings July 2017 - 363
Baylor University Medical Center Proceedings July 2017 - 364
Baylor University Medical Center Proceedings July 2017 - 365
Baylor University Medical Center Proceedings July 2017 - 366
Baylor University Medical Center Proceedings July 2017 - 367
Baylor University Medical Center Proceedings July 2017 - 368
Baylor University Medical Center Proceedings July 2017 - 369
Baylor University Medical Center Proceedings July 2017 - 370
Baylor University Medical Center Proceedings July 2017 - 371
Baylor University Medical Center Proceedings July 2017 - 372
Baylor University Medical Center Proceedings July 2017 - 373
Baylor University Medical Center Proceedings July 2017 - 374
Baylor University Medical Center Proceedings July 2017 - 375
Baylor University Medical Center Proceedings July 2017 - 376
Baylor University Medical Center Proceedings July 2017 - 377
Baylor University Medical Center Proceedings July 2017 - 378
Baylor University Medical Center Proceedings July 2017 - 379
Baylor University Medical Center Proceedings July 2017 - 380
Baylor University Medical Center Proceedings July 2017 - 381
Baylor University Medical Center Proceedings July 2017 - 382
Baylor University Medical Center Proceedings July 2017 - 383
Baylor University Medical Center Proceedings July 2017 - 384
Baylor University Medical Center Proceedings July 2017 - 385
Baylor University Medical Center Proceedings July 2017 - 386
Baylor University Medical Center Proceedings July 2017 - 387
Baylor University Medical Center Proceedings July 2017 - 388
Baylor University Medical Center Proceedings July 2017 - 389
Baylor University Medical Center Proceedings July 2017 - 390
Baylor University Medical Center Proceedings July 2017 - 391
Baylor University Medical Center Proceedings July 2017 - 392
Baylor University Medical Center Proceedings July 2017 - Cover3
Baylor University Medical Center Proceedings July 2017 - Cover4
http://www.brightcopy.net/allen/bapr/30-4
http://www.brightcopy.net/allen/bapr/30-3
http://www.brightcopy.net/allen/bapr/30-2
http://www.brightcopy.net/allen/bapr/30-1
http://www.brightcopy.net/allen/bapr/29-4
http://www.brightcopy.net/allen/bapr/29-3
http://www.brightcopy.net/allen/bapr/29-2
http://www.brightcopy.net/allen/bapr/29-1
http://www.brightcopy.net/allen/bapr/28-04
https://www.nxtbook.com/allen/bapr/28-3
https://www.nxtbook.com/allen/bapr/28-2
https://www.nxtbook.com/allen/bapr/28-1
https://www.nxtbook.com/allen/bapr/27-4
https://www.nxtbook.com/allen/bapr/27-3
https://www.nxtbookmedia.com