Sleep Medicine 10 (2009) 1005–1011

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Sleep Medicine

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Original Article

Sleep disordered breathing in an elderly community-living population:Relationship to cardiac function, insomnia symptoms and daytime sleepiness

Peter Johansson a,b,*, Urban Alehagen a,b, Eva Svanborg c,d, Ulf Dahlström a,b, Anders Broström c,e

a Department of Cardiology, Linköping University Hospital, S-58185 Linköping, Swedenb Department of Medicine and Health Sciences, Division of Cardiovascular Medicine, Faculty of Health Sciences Linköping University, S-58185 Linköping, Swedenc Department of Clinical Neurophysiology, Linköping University Hospital, S-58185 Linköping, Swedend Institution of Clinical and Experimental Medicine, Linköping University, S-58185 Linköping, Swedene Department of Medicine and Health Sciences, Division of Nursing Science, Linköping University, S-58185 Linköping, Sweden

a r t i c l e i n f o

Article history:Received 21 August 2008Received in revised form 14 January 2009Accepted 20 January 2009Available online 22 May 2009

Keywords:Sleep apnea syndromesAgingDyssomniaExcessive somnolence disorderLeft ventricular dysfunctionHeart failure

1389-9457/$ - see front matter � 2009 Elsevier B.V. Adoi:10.1016/j.sleep.2009.01.011

* Corresponding author. Address: Department of CaS-58185 Linköping, Sweden. Tel.: +46 13 222223; fax

E-mail addresses: peter.johansson@aries.vokby.se (Pliu.se (U. Alehagen), evasv@inr.liu.se (E. Svanborg), Ulf.Daandbr@imv.liu.se (A. Broström).

a b s t r a c t

Objective: To describe the prevalence of sleep disordered breathing (SDB) and its relationship to systolicfunction, different insomnia symptoms as well as excessive daytime sleepiness (EDS) in elderly commu-nity-living people. This has not been investigated previously.Method: Three hundred thirty-one subjects (71–87 years) healthy enough to be independently living intheir own homes underwent echocardiographic examinations and sleep respiratory recordings. Question-naires were used to evaluate insomnia symptoms and EDS.Results: Mild SDB (AHI 5–15) was found in 32%. Moderate SDB (AHI 15–30) occurred in 16%, and 7% hadsevere SDB (AHI > 30). Median AHI was significantly higher (p < 0.001) in those with mildly impaired sys-tolic function (AHI 11.7) and moderately impaired systolic function (AHI 10.9) compared to those withnormal systolic function (AHI 5.0). Impaired systolic function was associated with central sleep apnea(CSA) but not with obstructive sleep apnea. Concerning insomnia symptoms and EDS, only difficultiesin initiating sleep correlated significantly (p < 0.05) with AHI.Conclusion: SDB is common among the elderly. CSA may be related to impaired systolic function/heartfailure. However, detection of SDB in this population may be problematic since insomnia symptomsand EDS correlated poorly with SDB.

� 2009 Elsevier B.V. All rights reserved.

Grants and Sources: Financial support was provided by theHealth Research Council in the Southeast of Sweden Grant No.F2004-233.

1. Introduction

Sleep disordered breathing (SDB), defined as an apnea–hypo-pnea index (AHI) P 15, is estimated to affect about 4% of womenand 9% of men aged 30–60 years [1]. The prevalence is assumedto increase with age. In one study, 16% of the women and 24% ofthe men aged 60–70 had an AHI P 15 [2]. In another study, includ-ing subjects aged 65–99 years, 39% of the women and 51% of themen were found to have AHI P 20 [3]. In the latter age group heartfailure (HF) represents a major and increasing health problem, aswell as a possible cause for SDB [4]. It has previously been reported

ll rights reserved.

rdiology, University Hospital,: +46 13 222224.. Johansson), Urban.Alehagen@hlstrom@lio.se (U. Dahlström),

that 24–61% of these patients suffer from SDB [5–10]. The lowestprevalence rates (24% and 25%) were found in outpatients [7,10],whereas the highest rates (49–61%) were found in hospitalized pa-tients [5,6,8,9]. However, compared with the mean age of about 75years for HF patients living in the community [11], the mean age ofpatients in these studies ranged between 56 and 69 years [5–10].None of these studies compared the prevalence of SDB with age-matched populations without HF. The community-based SleepHeart Health Study showed that SDB was associated with HF [4].However, HF was defined as a positive answer by the participantsto the question of whether they had a diagnosis of HF, and not bytoday’s recommended methods [12]. These data cannot, therefore,be generalized to an elderly HF population, and therefore it is un-known if SDB in elderly community-living people with HF is a signof age or impaired systolic function.

Insomnia has been defined as difficulties initiating sleep (DIS),difficulties maintaining sleep (DMS), non-restorative sleep (NRS),or early morning awakenings (EMA) [13,14]. It is a frequent subjec-tive sleep complaint in the general population [14,15], often asso-ciated with excessive daytime sleepiness (EDS), and negativelyassociated with health related quality of life (Hr-QoL) in elderly

1006 P. Johansson et al. / Sleep Medicine 10 (2009) 1005–1011

subjects with or without chronic diseases such as HF [16–18]. SDBcan be a possible cause, but is hypothesized to be two distinct con-ditions in older and younger people [19,20]. In younger people,SDB has been related to subjective complaints of sleep distur-bances, such as insomnia [21] or EDS [1]. Insomnia in elderly peo-ple has been thought to be less influenced by SDB [22]. It has beenreported that the highest AHI and nadir oxygen levels become lesssevere as age increases [2,20]. This indicates that SDB may be moresevere in younger persons, and therefore the clinical impact of SDBin the elderly may be weaker. However, Ancoli-Israel et al. showedthat changes in RDI were only associated with changes in BMI,independent of age, in people 65 years old [23]. To our knowledgeonly one study has investigated the association between SDB,insomnia and EDS in community-living elderly, where elderly peo-ple with insomnia were found to have a lower rate of SDB [24].However, insomnia in this study was defined as a composite score.Another aspect is that SDB, i.e., obstructive sleep apnea (OSA), hasbeen found to have a different impact on different insomnia symp-toms [25]. Investigating the prevalence of SDB, its relationship toimpaired systolic function, the different insomnia symptoms, aswell as EDS must be seen as an important healthcare action to tar-get areas for interventions aimed to improve elderly peoples day-time functioning.

2. Aim

The aims of this study were (1) to describe the prevalence ofSDB and its relationship to impaired systolic function in an elderlypopulation living in the community and (2) to describe the rela-tionship between SDB and different insomnia symptoms, as wellas EDS.

3. Materials and methods

3.1. Participants

Data were collected between 2003 and 2005. All subjects werechosen from a cohort which had been investigated in a previousstudy which took place between 1998 and 2001 [26]. The primaryaim of that study was to investigate the prevalence of impaired leftventricular ejection fraction (LVEF)/HF in an aged population. Allinhabitants aged 65–82 years who were independently living intheir own homes in the rural municipality of Kinda in the southeastof Sweden were included. In total, 1130 persons were invited totake part. Of those, 876 agreed to participate (participation rate78%). Between January 2003 and May 2005 the cohort was con-tacted again and invited to participate in the present study. Ofthe initially 876 investigated subjects, a total of 675 subjectsunderwent a clinical and echocardiographic examination. Reasonsfor not participating were death, moving to other areas, severe ill-ness or a diagnosis of dementia. Of the 675 subjects, 346 (51%) alsoagreed to undergo sleep respiratory recordings. Those participatingin the sleep study did not differ from those who did not, with theexception of having more of a history of respiratory disease (asth-ma or chronic obstructive pulmonary disease; 17% vs. 12%,p = 0.04). All participants gave their informed written consent.The study protocol was approved by the ethics committee at thefaculty of health sciences, University of Linköping, Sweden, and isin accordance with the provisions of the Helsinki declaration.

3.2. Clinical examination, comorbidities and current treatment

Doppler echocardiographic (Accuson XP-128c) examinationswere performed with the patient in the left-supine position. LVEFwas determined semiquantitatively and was classified into three

classes, in which normal systolic function corresponded to aLVEF P 50%, mild impaired systolic function corresponded to anLVEF of 49–40%, and moderate impaired systolic function corre-sponded to an LVEF < 40%. In all analyses of patients and sleepstudy characteristics, individuals with normal systolic function(LVEF P 50%) were chosen to represent the reference group.

The diagnosis of diabetes mellitus was based on a history of dia-betes, current treatment (oral therapy or insulin) or a fasting bloodglucose value P7 mmol/l.

Hypertension was assessed if the patients had previously re-ceived the diagnosis or had a resting blood pressure of more than140/90 mm Hg.

Ischemic heart disease (IHD) was defined as a history of anginapectoris and/or myocardial infarction and/or coronary angioplastyand/or coronary bypass surgery.

Respiratory disease was assessed if the participants had a his-tory of asthma or chronic obstructive pulmonary disease, or wereon current treatment (b2 agonists and/or inhaled corticosteroids).

TIA/stroke was defined as a history of TIA and/or stroke.

3.3. Sleep study

The sleep studies were performed during one-night in the pa-tients homes with polygraphic equipment (Embletta, Flaga MedicalInc, Reykjavik, Iceland). The recording included airflow measuredby a nasal pressure cannula, posture, physical motions, abdominaland thoracic movements by an inductive plethysmograph, and fin-ger pulse oximetry. The Embletta has been found to be a valid diag-nostic tool for SDB in patients with possible obstructive sleepapnea syndrome [27] and has also been used in studies on patientswith HF [6,28].

Apneas, hypopneas and SDB severity were scored according tothe American Academy of Sleep Medicine Task Force guidelines[29]. No SDB was defined as an AHI < 5, mild SDB was definedas an apnea–hypopnea index (AHI) of 5–15, moderate SDB asAHI 15–30, and severe SDB as AHI P 30. Participants were con-sidered to have OSA or central sleep apnea (CSA) if more than50% of their apneas were obstructive or central, respectively.However, as the cut-offs AHI P 5, AHI P 10 and AHI P 15 havebeen used to define the presence of SDB in several studies onpatients with HF [5,6,10,30,31], these cut-offs were used in someof our analyses. The start and end of the analysis period wereboth set according to the combination of information providedby the participants (sleep-log and interview), tracing qualityand breathing patterns. Sleep scorings were done by the mainauthor (PJ), who had no knowledge about the echocardiographicfindings.

3.4. Questionnaires

The Uppsala Sleep Inventory (USI) [32] was used to measure theseverity of insomnia symptoms (DIS, DMS, NRS, EMA). The ques-tions about insomnia symptoms were to be answered on a five-point Likert-type scale, i.e., no problems (1), small problems (2),some problems (3), great problems (4) and very great problems(5). Symptoms of insomnia were considered present if some prob-lems or more were reported. The USI has been used in surveys onelderly people living in the community [33] and on patients withcardiovascular disease [34] and HF [18].

The Epworth Sleepiness Scale (ESS) was used to measure EDS. Acut-off value P10 indicated EDS [35].

3.5. Statistical analysis

Descriptive statistics were used to describe the study popula-tion. Categorical data were described with percentages and num-

Table 1Characteristics of the population and subjective sleep complaints across the severity of SDB.

Characteristics AHI

<5 P5 P15 P30 p1 p2

No SDB Mild SDB Moderate SDB Severe SDB(n = 148, 45%) (n = 107, 32%) (n = 53, 16%) (n = 23, 7%)

Male, % (n) 43 (64) 53 (57) 55 (29) 61 (14) 0.2 0.035Age, mean (SD) 78.6 (3.5) 78.1 (2.9) 78.7 (3.2) 78.5 (3) 0.48 0.77SBP, mean (SD) 148 (18) 149 (19) 148 (23) 146 (17) 0.91 0.64DBP, mean (SD) 74 (9) 75 (9) 75 (9) 76 (9) 0.81 0.36BMI, mean (SD) 26.7 (3.6) 28.2 (5) 27.4 (4.3) 29.9 (4.3) 0.001 0.02

ComorbiditiesDiabetes, % (n) 22 (32) 22 (23) 32 (17) 22 (5) 0.43 0.35HT, % (n) 71 (105) 72 (77) 81 (43) 70 (16) 0.52 0.4IHD, % (n) 21 (31) 27 (29) 36 (19) 26 (6) 0.2 0.06RD, % (n) 18 (27) 16 (17) 11 (6) 17 (4) 0.7 0.36TIA/Stroke, % (n) 5 (8) 8 (9) 15 (8) 17 (4) 0.08 0.02

MedicationACEI/ARB, % (n) 21 (31) 34 (36) 32 (17) 26 (6) 0.12 0.06B-blockers, % (n) 27 (40) 43 (46) 57 (30) 44 (10) 0.001 <0.01Digoxin, % (n) 4 (6) 7 (8) 6 (3) 4 (1) 0.69 0.52Diuretics, % (n) 32 (48) 35 (37) 38 (20) 48 (11) 0.52 0.51Hypnotics, % (n) 15 (23) 13 (14) 13 (7) 22 (5) 0.73 0.97

Insomnia symptomsDIS, % (n) 36 (53) 38 (41) 51 (27) 52 (12) 0.15 0.04DMS, % (n) 65 (96) 63 (67) 66 (35) 61 (14) 0.95 0.84NRS, % (n) 36 (54) 41 (44) 49 (26) 52 (12) 0.27 0.06EMA, % (n) 43 (63) 36 (38) 38 (20) 44 (10) 0.68 0.5

Excessive daytime sleepinessESS, mean (SD) 6.5 (3.8) 6.6 (3.8) 6.8 (3.5) 6.7 (4.1) 0.81 0.57ESS P 10, % (n) 18 (27) 21 (22) 24 (13) 22 (5) 0.8 0.36

SDB groups are categorized according to an apnea-hypopnea index <5, P5, P15 or P30. Significant p-values are bolded. Key: ACEI – angiotensin converting inhibitor; ARB –angiotensin receptor blockers; AHI – apnea-hypopnea index; B-blockers – beta blockers; BP – blood pressure; BMI – body mass index; DBP – diastolic blood pressure; DIS –difficulties initiating sleep; DMS – difficulties maintaining sleep; ESS – epworth sleepiness scale; EMA – early morning awakening; HT – hypertension; IHD – ischaemic heartdisease; NRS – non restorative sleep; RD – respiratory disease; SBP – systolic blood pressure; SD – standard deviation; SDB – sleep disordered breathing; TIA/stroke – transischaemic attack/stroke.p1 p-value for comparison of several groups with analysis of variance (ANOVA), v2 or Kruskal-Wallis test.p2 p-value for the correlation between the different variables and SDB groups.

P. Johansson et al. / Sleep Medicine 10 (2009) 1005–1011 1007

bers, whereas continuous data were described with their meansand standard deviations. Variables describing sleep disorderedbreathing which were skewed, AHI for example, were describedwith their median and interquartile range (IQR). Differencesacross the SDB and LVEF groups were evaluated with overallv2 tests for categorical variables, analysis of variance for nor-mally distributed continuous variables and Kruskal–Wallis onnon-Gauss distributed continuous variables. In these analyses, anon-significant difference between categorizations of groupsdoes not exclude that differences could exist if other categoriza-tions (i.e., other AHI groups or LVEF groups) were used. To detectsuch correlations, Pearson’s or Spearman’s rank correlations wereused. Differences between groups for categorical variables weremeasured with v2 tests or Fischer’s exact test. For continuousvariables, the Students t-test or Mann–Whitney U-test wereused. Logistic regression analysis (backward procedures) wasused to examine a possible independent relationship betweenimpaired systolic function and SDB. AHI P 10 and AHI P 15were used as dependent variables. Few participants were foundto have moderately impaired systolic function (n = 22). Toincrease the power in the statistical analysis, we thereforeamalgamated those with mild impaired (n = 33) and moderateimpaired systolic function into one group, impaired systolicfunction. Variables in Table 1 that had an univariate correlationof p < 0.05 with SDB, i.e., age, male gender, body mass index,IHD, TIA/stroke, beta-blockers and DIS, were used as covariates.A two-tailed p < 0.05 was considered significant. Statisticswere processed with the SPSS version 16.0 (SPSS Inc, Chicago,IL, USA).

4. Results

4.1. Participants

Of the 346 sleep recordings, 15 were lost due to technical failure.Thus the final study population consisted of 331 persons. Populationcharacteristics, co-morbidities and medications across different SDBgroups are given in Table 1. The mean age was 78 years, and 49%were males. Sleep recordings were performed in a median of 12 days(IQR 12) after the clinical and echocardiographic examination. Char-acteristics that significantly correlated with the severity of SDB weremale gender, BMI, TIA/stroke, beta-blockers and DIS.

4.2. Prevalence of sleep disordered breathing and its relationship to leftventricular ejection fraction

AHI ranged between 0 and 69 (median 6.1, IQR 12.4). A total of32% had mild SDB, whereas moderate or severe SDB occurred in16% and 7% of the subjects, respectively (Table 1). In mild and mod-erate SDB, OSA was more than twice as common as CSA, whereas inthose with severe SDB, CSA was almost as common as OSA (Fig. 1).

There were significant associations between impaired systolicfunction and almost all SDB variables (Table 2). The median AHIwas more than twice as high in the groups with mild and moderateimpaired systolic function (AHI 11.7 and 10.9, respectively) com-pared to those with normal systolic function (AHI 5.0) (p < 0.001).No differences were detected between those with mild or moderateimpaired systolic function. As illustrated in Fig. 2, those with nor-mal systolic function had a significantly lower prevalence of SDB

52%70%69%

48%28%28%

010

2030

405060

7080

90100

SevereModerateMild

OSA CSA

Distribution of OSA and CSA across severity of SDB

Fig. 1. Distribution (%) of obstructive sleep apnea (OSA) and central sleep apnea (CSA) across the severity groups of sleep disordered breathing (SDB).

Table 2Patient and sleep study characteristics by LVEF groups.

Characteristics and sleep study variables LVEF P 50% LVEF 49–40% LVEF < 40%(n = 276) (n = 33) (n = 22) p1 p2

Male, % (n) 43 (118) 76 (25) 96 (21) <0.001 <0.001Age, mean (SD) 78.4 (3.2) 78.9 (3) 79.7 (3.5) 0.12 0.04BMI, mean (SD) 27.7 (4.4) 27 (4.0) 26.6 (3.8) 0.42 0.25SBP, mean (SD) 149 (19) 145 (17) 145 (27) 0.5 0.26DBP, mean (SD) 74 (9) 72 (9) 75 (11) 0.38 0.65

OSA,(AHI P 5, 15), % (n) 36 (100)/14 (39) 46 (15)/18 (6) 36 (8)/ 18 (4) 0.58/0.74 0.48/0.44CSA, (AHI P 5, 15), % (n) 12 (34)/5 (15) 27 (9)/21 (7) 50 (11)/18 (4) <0.001/<0.001 <0.001/<0.001

AHI/h, md (IQR) 5.0 (10) 11.7 (17.2) 10.9 (17.2) <0.001 <0.001AI/h, md (IQR) 1.4 (4.8) 5.3 (16.8) 5.2 (14) <0.001 <0.001HI/h, md (IQR) 2.6 (5.3) 5.9 (5.8) 3.7 (9.6) 0.02 0.005OAI/h, md (IQR) 0.6 (2.6) 2.3 (5.6) 0.85 (5.3) 0.02 0.007CAI/h, md (IQR) 0.2 (0.8) 1.1 (4) 1.9 (3.4) <0.001 <0.001MixI/h, md (IQR) 0 (0.2) 0.2 (1.3) 0.2 (0.6) <0.001 <0.001ODI h, md (IQR) 4.6 (9) 9 (19.2) 9.8 (14.9) <0.001 <0.001Min O2, mean (SD) 84.2 (5.1) 83.4 (4.3) 82.8 (4.5) 0.75 0.05Mean O2, (SD) 94.4 (1.8) 94.2 (1.7) 94.3 (1.7) 0.14 0.64

LVEF are categorized according to normal (LVEF P 50%), mild impaired (LVEF 49-40%) or moderate impaired systolic function (LVEF<40%). Significant p-values are bolded.Key: AHI – apnea-hypopnea index; AI – apnea index; BMI – body Mass Index; CAI – central apnea index; CSA – central sleep apnea; DBP – diastolic blood pressure; HI –hypopnea index; IQR – interquartile range; LVEF – left ventricular ejection fraction; MixI – mixed apnea index; OAI – obstructive apnea index; OSA – obstructive sleep apnea;ODI – oxygen desaturation index; O2 – Oxygen; SD – standard deviation; SDP – systolic blood pressure.p1p-value for comparison of several groups with, Analysis of variance (ANOVA), v2 or Kruskal-Wallis test.p2p-value for the correlation between the different variables and the LVEF groups.

5

20

32

50

0.13

0.015

0.003

0.015

<0.001

0.03

0.069

0.04

0

10

20

30

40

50

60

70

80

90

100

AHI 5 AHI 10 AHI 15 AHI 30

Per

cen

tag

e

LVEF 50 LVEF49-40 LVEF<40%

91

91

73

58 54

3936

1218

Prevalence of SDB in the different LVEF groups

Fig. 2. LVEF are categorized according to normal (LVEF P 50%), mild impaired (LVEF 49–40%) or moderate impaired systolic function (LVEF < 40%). Numbers above the barsdescribe the significances between the LVEF groups. Numbers within the bars describe the prevalence of SDB in the respective LVEF group. Key: AHI/h – apnea–hypopneaindex/hour; LVEF – left ventricular ejection fraction.

1008 P. Johansson et al. / Sleep Medicine 10 (2009) 1005–1011

Table 3Logistic regression analysis of the association between LVEF and SDB.

AHI P 10 AHI P15

OR (CI 95%) v2 p OR (CI 95%) v2 p

B-blockers 1.8 (1.1–2.9) 3.2 0.019 B-blockers 1.9 (1.1–3.3) 5.5 0.019DIS 1.9 (1.1–3.2) 5.4 0.02TIA/stroke 2.7 (1.2–6.1) 5.5 0.019

LVEF LVEFP50% Ref P50% Ref<50 2.5 (1.4–4.7) 8.9 0.003 <50% 2.0 (1.1–3.9) 4.7 0.03

Final results from the stepwise backward regression analysis. Left ventricular ejection fraction (LVEF) are categorized according to normal (LVEF P 50%) or impaired systolicfunction (LVEF < 50%). SDB are defined as AHI P 10 or AHI P 15. Age, male gender, body mass index, ischeamic heart diseases, TIA/stroke, beta-blockers and DIS were used ascovariates in the analysis. Key: AHI – Apnea-hypopnea index; B-blockers – Beta-blockers; CI – Confidence Interval; DIS – Difficulties initiating sleep; LVEF – Left ventricularejection fraction; OR – Odds Ratio; SDB – Sleep disordered breathing; TIA/stroke – Trans ischaemic attack/stroke.

50%

27%12%

27%

24%

7%

18%

21%

5%

0102030405060708090

100

LVEF 50% LVEF49-40% LVEF<40%

AHI 5 AHI 10 AHI 15

*0.019

*0.001

**0.019

*0.001

**0.001

**0.001

Prevalence of CSA according different AHI cut-offs in the different LVEF groups.

Fig. 3. The bars represent normal (LVEF P 50%), mild impaired (LVEF 49–40%) and moderate impaired systolic function (LVEF < 40%). The different values within the barsdescribe the percentages of CSA according to AHI cut-offs P5, 10, 15. The numbers outside the bars represent the p-values for the differences of CSA at AHI P 5, 10, 15between the different LVEF groups. Key: AHI/h – apnea–hypopnea index; LVEF – left ventricular ejection fraction. *LVEF 49–40% compared with LVEF P 50% at same AHI level.**LVEF < 40% compared with LVEF P 50% at same AHI level.

P. Johansson et al. / Sleep Medicine 10 (2009) 1005–1011 1009

according to the AHI cut-off levels 5, 10, 15 and 30. The prevalenceof SDB did not significantly differ between the groups with mild ormoderate impaired systolic function. To examine if impaired sys-tolic function independently was associated with SDB, backward lo-gistic regression analysis was used. Besides the measures of systolicfunction, age, male gender, BMI, IHD, TIA/stroke, beta-blockers andDIS were also entered in the regression models. Factors statisticallyassociated with SDB, as indicated by an AHI P 10, were impairedsystolic function (LVEF < 50%; odds ratio [OR] 2.5, p = 0.003) andbeta-blockers (OR 1.8, p = 0.03). Factors statistically associated withAHI P 15, were impaired systolic function (LVEF < 50%; OR 2.0,p = 0.03), beta-blockers (OR 1.9, p = 0.019), DIS (OR 1.9, p = 0.02)and TIA/stroke (OR 2.8, p = 0.01) (Table 3).

A total of 36% and 14% of those with normal systolic functionhad OSA according to AHI P 5 or P15. This was not significantlydifferent compared to those with mild or moderate impaired sys-tolic function (Table 2). However, regardless of AHI cut-off level,CSA was significantly more common in study participants withmild or moderate impaired systolic function than in those withnormal systolic function (Fig. 3). No significant difference wasfound between those with mild or moderate systolic function. Ina subsequent analysis we found that mild and moderate impairedsystolic function still was associated with CSA after adjustment forage (data not shown).

4.3. Sleep disordered breathing, insomnia symptoms and excessivedaytime sleepiness

The analyses showed a marginal association of SDB and DIS, andno association of SDB and EDS was found (Table 1). However, DIS

was significantly more common in those with AHI P 15 comparedto those with AHI < 15 (p = 0.024). None of the insomnia variablesor EDS showed any significant association with LVEF.

5. Discussion

This is one of the first studies to objectively examine the prev-alence of SDB in older people healthy enough to be living in thecommunity. The aim was to find possible associations betweenSDB and systolic function as measured by echocardiography, aswell as to describe the association between SDB, different insomniasymptoms and EDS.

5.1. Prevalence of sleep disordered breathing and association withcardiac function and heart failure

We found SDB to be common among the elderly. More than half(55%) of the studied population had an AHI P 5. Mild SDB wasfound in 32% of the population, whereas 23% had moderate/severeSDB (Table 1). These numbers are comparable with data presentedfrom the Sleep Heart Health Study, which found that approxi-mately 55% of the subjects in the age cohorts 70–79 and 80–99had AHI P 5. Of these, 33% had mild SDB, whereas 20% had moder-ate/severe SDB [19].

SDB was also common in those with normal systolic function50% had an AHI P 5. This indicates that SDB to some extent maybe seen as a part of the aging process, i.e., an age dependent phe-nomenon. Another explanation for the high prevalence of SDB inthe elderly might be that higher age often brings a growing num-ber of people with chronic diseases, such as HF. In our study

1010 P. Johansson et al. / Sleep Medicine 10 (2009) 1005–1011

SDB, and especially CSA, was more prevalent in those with mildand moderate impaired systolic function than in those with normalfunction (Fig. 2, Table 2). After controlling for several different fac-tors impaired systolic function (LVEF < 50%) was still indepen-dently associated with AHI P 10 and AHI P 15 (Table 3).However, because of the low number of participants with moder-ately impaired systolic function (LVEF < 40%, n = 22) our analysisand conclusions are somewhat limited. On the other hand, a majoradvantage with our study design is that we investigated a generalelderly population living in the same geographical area and of thesame age regarding objective evidence of impaired systolic func-tion as well as SDB. We also used control groups, i.e., individualswith and without SDB and with normal systolic function who weredrawn from the same sample. This has, to our knowledge, neverbeen done before, and despite our limitations we therefore believethat our results regarding the association between cardiac functionand AHI P 10 and AHI P 15 are valid.

We found that CSA was significantly more common in thosewith mild and moderate impaired systolic function than in thosewith normal systolic function. But this was not found for OSA (Table2, Fig. 3). Hypertension has been reported to be associated with OSA[36–38] as well as to be a risk factor for the devolvement of HF [12].Therefore, OSA might be seen as playing a role in the pathogenesisand progression of cardiac failure, whereas CSA can be seen as aconsequence of impaired systolic function [39]. Studies from largecommunity cohorts have, however, shown that the association be-tween OSA and hypertension decreases with age [37,38]. In elderlypeople OSA has been shown to cause less respiratory efforts in re-sponse to upper airway occlusion [40] and is probably, therefore,less likely to cause adrenergic activation and cardiovascular stress.This could explain the lack of association between OSA and im-paired systolic function in our study. Findings regarding the associ-ation between SDB and mortality in elderly people seem to besomewhat inconsistent. Mant et al. and Ancoli-Israel et al. reportedno association between SDB and mortality in community dwellingelderly [41,42]. A recent study that compared survival in elderly pa-tients investigated for SDB to a matched control population had thesame experiences for those with mild or severe SDB. The group withmoderate SDB had, however, surprisingly significantly higher sur-vival rates [43]. However, these studies did not provide any survivalrates in relation to OSA or CSA. Breathing pattern may still be ofimportance since Ancoli-Israel et al. reported that CSA comparedto OSA was a poor prognostic sign in patients with HF (mean ageof 69 years) [44]. But prevalence rates of CSA and OSA establishedby a single night of monitoring may be an uncertain measure. Vaziret al. reported that 42% out of the studied HF patients, who wereclassified as CSA or OSA on their first night, shifted classificationthe following three nights [45]. On the other hand, this did not im-pact the AHI since the study found that an AHI P 15 remained sta-ble during the four night study period. Reported AHI levels in ourstudy are probably more representative than the prevalence of spe-cific SDB types. Due to economical reasons it was not possible for usto perform more than a one night respiratory sleep study. Despitethis, we believe that our reported prevalence of CSA is of interestas only one publication has previously studied the prevalence ofCSA in an elderly population [20]. Compared to the 16% of the totalpopulation found to have CSA in our study (Table 2), Bixler et al. re-ported 12% [20]. However, their study included only males. Theauthors suggested that CSA could be seen as a normal part of aging[20], but their study did not include any variables of systolic func-tion. In our study impaired systolic function was associated withCSA after controlling for age. However, this association is, of course,only correlational, since the design of the study does not allow anyconclusions concerning causal relationships.

Difficulties arise when comparing our data with other studiesthat have examined the prevalence of SDB in HF patients. Some

studies have used an LVEF < 45% to define HF [5,8,10,30,46]; be-sides this, different sleep recording and scoring methods, as wellas different age groups have been used [5,6,8–10]. Using the cut-off level AHI P 15, 36% with moderate impaired systolic function(LVEF < 40%) had SDB in our study (Table 3, Fig. 3). Other studiesusing the same cut-off levels report rates of 24–61% [5–10]. Thestudy by Rao et al. is most similar to our study [7]. They includedolder outpatients (mean age 69 years), used a polygraphic devicein the patients’ homes, and the diagnosis of HF was based onLVEF < 40%. A total of 24% in that study had an AHI P 15 comparedwith the 36% in our study. However, Rao et al. did not record air-flow, only oximetry [7]. The prevalence of SDB would thereforehave been underestimated since apneas that were not followedby a desaturation would not have been detected. However, ourstudy and the study by Rao et al. suggest that about 20–40% of el-derly people with moderate impaired systolic function(LVEF < 40%) have moderate to severe SDB [7].

5.2. Sleep disordered breathing and its association with daytimesleepiness and insomnia symptoms

This study shows that elderly persons may have a high preva-lence of SDB, but without any obvious health consequences, suchas more sleep disturbances or daytime sleepiness.

Sleepiness has been regarded as a cardinal symptom of SDB, butwe could not detect any associations between EDS, as measuredwith the Epworth Sleepiness Scale and SDB. A recent study re-ported that patients with OSA and EDS sleep longer and more effi-ciently than those without EDS [47]. In that study there were noclinical differences in SDB variables between OSA patients withor without EDS, indicating that other factors than SDB are impor-tant for the presence of EDS. Bixler et al. reported depression,BMI, diabetes and a subjective estimate of sleep duration in the ab-sence of objective indication of sleep loss to be more importantthan SDB for the presence of EDS [48]. They also reported thatthe prevalence of EDS decreased with increasing age between theages 30–75 years. The highest prevalence rates were found in thosebelow 30 years and above 75 years. Bixler et al. discussed that EDSin the oldest age groups to a higher extent could be associated withdifferent health problems than with decreased nocturnal sleep effi-ciency [48]. Therefore, complaints of EDS, especially among the el-derly, can be seen as a poor clinical sign of SDB.

We could not find any association between SDB and the insom-nia symptoms (DMS, NRS, EMA) (Table 2). The same result wasfound in another study on the elderly, but that study only mea-sured insomnia as a composite score [24]. However, we foundDIS to be more common in those with AHI P 15. Because of thepoor association between EDS and SDB in our study, occurrenceof DIS is probably not due to more sleep or naps during daytimein those with SDB. Chung examined the association between DIS,DMS and EDS in patients with OSA. He found longer sleep latenciesin the multiple sleep latency test in those who complained of DISthan in patients without insomnia or DMS [25]. The author sug-gested that those with DIS were in a state of hyperarousal. In HFpatients a disturbed sleep can be caused by negative thoughts,stress, anxiety (i.e., hyperarousal) [49] and/or depression [50]. Inour study impaired systolic function, as well as TIA/stroke wasassociated with SDB. One may suspect that DIS could be a conse-quence of the distress (i.e., anxiety and/or depressive symptoms)caused by a disease such as HF or TIA/stroke, rather than SDB itself.But the population included in this study was healthy enough to beindependently living in their own homes, respond to question-naires, and answer to written and verbal information about thesleep study. The main researcher (PJ) met all study participantsin their own homes and judged that no one suffered from severemental health problems, such as major depression or dementia.

P. Johansson et al. / Sleep Medicine 10 (2009) 1005–1011 1011

6. Conclusion

This study, performed in an elderly population living in thecommunity, demonstrates that about one quarter of such a popu-lation may have moderate/severe SDB, as defined by an AHI P 15.SDB (i.e., AHI P 10 and AHI P 15) and CSA, especially, were inde-pendently associated with impaired systolic function. Our studyshows that detection of SDB by means of different insomnia symp-toms or EDS might be problematic. On the other hand, DIS weremore common in individuals with an AHI P 15. The effects ofOSA and CSA per se on elderly with or without HF are unclear atpresent. A future longitudinal study might show whether thereare any causal relationships between CSA/OSA and developmentof HF. More research is also needed to investigate the impact ofobjective measures of SDB on subjective complaints of sleep, day-time consequences and morbidity/mortality.

Conflict of interest

None.

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