Continuous positive airway pressure treatment for sleep apnoea: compliance increases with time in continuing users

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1 Eur Respir J 2006; 27: DOI: / CopyrightßERS Jourals Ltd 2006 Cotiuous positive airway pressure treatmet for sleep apoea: compliace icreases with time i cotiuig users M. Sucea, G. Liistro, G. Aubert, D.O. Rodestei ad T. Pieters ABSTRACT: Cotiuous positive airway pressure (CPAP) remais the best treatmet for sleep apoea sydrome (SAS). I the 1990s, may authors reported o daily compliace, but all of the studies utilised relatively short periods of follow-up that did ot exceed a few years. The mea aual rate of CPAP use i patiets with SAS was prospectively recorded. I the curret study, the results are preseted alog with compliace data from patiets who started CPAP betwee 1991 ad 1998 ad were still usig it by the ed of The cohort was chose i order to obtai o5 yrs of follow-up for each patiet. I total, there were 204 patiets. For the whole group, mea SD compliace reached ad mi after 1 ad 10 yrs, respectively. There was o sigificat chage i the first 2 yrs, with a sigificat icrease from the third year owards. Compliace, or its evolutio over time, was ot correlated either to the baselie polysomographical data (except slightly for the CPAP pressure), to the differece of these data before ad uder CPAP therapy, to the age of retiremet or to chages i the marital status. I coclusio, very log-term compliace with cotiuous positive airway pressure icreases by a mea of 8 mi?day -1 per year of follow-up i patiets with sleep apoea sydrome. KEYWORDS: Compliace, cotiuous positive airway pressure, sleep apoea sydrome AFFILIATIONS Peumology Uit, Cliiques Uiversitaires Sait-Luc, Uiversité Catholique de Louvai, Brussels, Belgium. CORRESPONDENCE T. Pieters Service de Peumologie Cliiques uiversitaires Sait-Luc Uiversité Catholique de Louvai Aveue Hippocrate Brussels Belgium Fax: thierry.pieters@cli.ucl.ac.be Received: July Accepted after revisio: November Compliace with medical treatmet is worth cosiderig both i acute ad chroic diseases. It is oe of the major determiats of treatmet failures. I epilepsy, almost half of the patiets experiece a seizure durig follow-up after missig a medicatio itake [1]. Factors ifluecig compliace deped o the followig: 1) patiet persoality; 2) iteractios betwee the prescriber ad the patiet or family; 3) the characteristics of the treatmet; 4) its price; ad 5) the ature of the disease. For istace, it could be thought that compliace i chroic osymptomatic diseases, revealig their deleterious effects years or decades after their diagosis, such as hypertesio or type II diabetes mellitus, requires much more ivolvemet from the patiet tha compliace i diseases where symptoms are dramatic ad upredictable, such as epilepsy, or compliace amog oral cotraceptive users. Nevertheless, treatmet compliace seems o better i epilepsy tha i systemic arterial hypertesio [2]. Cotiuous positive airway pressure (CPAP) has remaied the best treatmet for sleep apoea sydrome sice its itroductio i Medical staff became rapidly aware of the compliace problems that could be experieced with a exteral mechaical device. Utilisatio rates measured objectively with time couters icluded i the CPAP devices raged betwee 65 ad 85% of the days moitored [3 5]. Most of the studies coducted i the 1990s had relatively short periods of follow-up ad were isolated surveys. It has bee previously show that patiets used their CPAP for mea SD h?day -1 ad that this use was quite stable after treatmet oset o two successive follow-up periods of 670 ad 390 days o average ( ad h, respectively) [5]. I the very log term (.3 yrs), it is ot kow how patiets will behave with respect to their treatmet. KRIEGER et al. [6] reported o 728 obstructive sleep apoea patiets who were followed durig a mea (rage) period of 1,176 (27 4,203) days. The mea compliace over time was h, which icreased with time. Data were ot show, but oe figure idicated a mea use icreasig from 5.4 to 6.2 h durig a average follow-up of 4.5 yrs. Sice the umber of patiets was ot costat, the fact that the icrease was the cosequece of the elimiatio of poor users caot be discouted. Europea Respiratory Joural Prit ISSN Olie ISSN c EUROPEAN RESPIRATORY JOURNAL VOLUME 27 NUMBER 4 761

2 SLEEP APNOEA SYNDROME, CPAP AND COMPLIANCE M. SUCENA ET AL. Sice 1991, the curret authors have prospectively recorded the mea aual rate of CPAP use i patiets with obstructive sleep apoea sydrome. To add ew data to the study by KRIEGER et al. [6], the preset study was coducted i a fixed populatio, i.e. those patiets who were usig CPAP by the ed of 2003 ad had started treatmet betwee 1991 ad MATERIAL AND METHODS The study cohort cosisted of all patiets with obstructive sleep apoea sydrome startig treatmet with CPAP betwee the start of 1991 ad the ed of 1998, who were still beig treated by the ed of The cohort was chose retrospectively so that all patiets would have at least a 5-yr follow-up. As is the rule i the Belgia social security system, CPAP was oly cosidered for patiets with sleep apoea sydrome complaiig of daytime sleepiess ad/or sorig ad showig, o a full-ight diagostic polysomography, a apoea/hypopoea idex (AHI) o20 ad a movemet arousal idex (MAI) o30 per hour of sleep. Some rare patiets ot fulfillig these criteria also received CPAP therapy, maily i cases presetig with clear-cut sleepiess ad a AHI o20, but without excessive sleep fragmetatio i the diagostic polysomography. Details of the methods used were described previously [7]. Movemet arousal was defied as the reappearace of a alpha rhythm i the electroecephalogram durig a sleep epoch, accompaied by a icrease i chi electromyogram activity (both i rapid eye movemet (REM) ad o-rem sleep) ad lastig for o2 s. A apoea was defied as cessatio of airflow for o10 s, whereas a hypopoea was defied as a.50% reductio i airflow for o10 s. The hypopoea defiitio required a.3% drop i arterial oxyge saturatio. Therefore, the desaturatio idex (DI; umber of desaturatios o4% per hour of sleep) was take as the AHI. Oce the diagosis was established, patiets were offered a CPAP trial. Patiets were hospitalised for 3 4 ights i order to make them comfortable with treatmet. Durig this period, patiets were istructed i the use of CPAP ad could try differet types of masks, as well as get acquaited with the apparatus. CPAP was oly offered to those patiets who accepted it ad if the polysomography uder CPAP therapy (which directly followed the habituatio trial) showed a clear improvemet or ormalisatio of MAI, DI ad sleep architecture. The device was delivered to the patiet s home by a commercial delegate ot belogig to the curret authors uit. This procedure did ot chage throughout the study period. Oce a year, patiets were see i the outpatiet s cliic. There was o other reiforcemet for treatmet, but, i case of trouble or questios, patiets could telephoe the uit or the techical support service at will. CPAP was free of charge for the patiets. Belgium s social security aually reimburses the total cost of the equipmet ad maiteace, except the humidifier, provided that the mea daily compliace is.3 h. The maiteace of the CPAP device is also performed yearly at home. The rate of use reported i the study came from the yearly readig of the built-i time couter by the techical delegate, divided by the umber of days separatig two readigs. I other words, data were collected prospectively. Of this value, 10% was subtracted to give the daily compliace accordig to studies comparig ruig time ad effective use [4, 8, 9]. I order to obtai data o the proportio of patiets remaiig o CPAP therapy for log periods, the patiets who quit CPAP ad the reasos (itolerace, death or cure) were recorded from 1997 owards. Therefore, the quit rate ad the reasos for quittig were available for the patiets of the study groups icluded durig the period of To gai iformatio o variables that could explai the evolutio of compliace with time, ad that were ot icluded i the preset database, telephoe iterviews were coducted o all patiets who started o CPAP therapy i 1994 ad Questios were asked regardig ay chage i family status (widowig, divorce or marriage) ad the year of retiremet for patiets havig chaged their professioal status from active workers to retiremet. The iterviews were performed i July The curret authors have oly systematically recorded subjective sleepiess usig the Epworth Sleepiess Scale sice Therefore, such data are ot evaluated i this study. The sleep laboratory used had two beds equipped for polysomographical studies. Statistical aalysis First, the differeces betwee the groups (withi the year treatmet started) were assessed by ANOVA to check the samples homogeeity for all of the variables studied. The differeces withi the year of treatmet ad betwee successive years of treatmet were assessed by ANOVA, followed by post hoc cotrasts (least sigificat differece) as appropriate. The betwee-group sums of squares were partitioed ito tred compoets to test for a tred of the compliace across the ordered levels of the years of treatmet usig the cotrasts i ANOVA. A regressio aalysis was used to verify the relatioship betwee compliace ad the other variables. RESULTS The mea SD age of the 204 patiets icluded i the preset study was yrs. A total of 16 females (8%) were icluded. Table 1 shows the characteristics of the populatio at the time of diagosis; 10 patiets (5%) did ot fulfil the Belgia criteria for CPAP treatmet. All of the patiets had a DI of o20. I this subset, mea (rage) MAI was 22 (5 29). From TABLE 1 Mai characteristics of the study populatio Mea Media Subjects 204 Age yrs ( ) BMI kg?m ( ) DI (20 117) DI uder CPAP (0 69) MAI (5 116) MAI uder CPAP (1 52) CPAP pressure cmh 2 O (5 16) Data are preseted as mea SD ad media (rage), uless otherwise stated. BMI: body mass idex; DI: desaturatio idex i the diagostic polysomography; CPAP: cotiuous positive airway pressure; MAI: movemet arousal idex i the diagostic polysomography. 762 VOLUME 27 NUMBER 4 EUROPEAN RESPIRATORY JOURNAL

3 M. SUCENA ET AL. SLEEP APNOEA SYNDROME, CPAP AND COMPLIANCE Compliace mi Years after CPAP oset 1991 to 1998, 27, 26, 14, 21, 24, 22, 42 ad 28 patiets, respectively, were icluded each year ad were still usig CPAP at the ed of There was o sigificat chage i body mass idex (BMI) amog the differet groups of patiets throughout the years. The DI was also stable, but the mea SD MAI sigificatly decreased from 1991 to 1993 (68 22 ad 45 15, respectively) ad remaied stable thereafter (p,0.0001). I a uivariate aalysis, o correlatio was foud betwee the compliace durig the first year of CPAP treatmet ad BMI, age, DI, MAI, ad differece i DI ad MAI betwee the diagostic ad the therapeutic CPAP polysomography. Compliace was slightly but sigificatly correlated with CPAP pressure (r50.145; 95% cofidece iterval ; p50.04) so that a higher CPAP pressure was liked to a higher compliace durig follow-up. Compliace icreased progressively ad sigificatly over time (fig. 1). Mea daily compliace reached , ad mi after 1, 5 ad 10 yrs, respectively. The mea slope of compliace icrease was 8 mi?yr -1. For the study populatio as a whole, the differece i compliace with follow-up became sigificat from the third year of treatmet owards. Figure 2 shows the evolutio of compliace i the eight groups of patiets startig treatmet betwee 1991 ad Compliace icreased i the same way for each group. The evolutio was statistically sigificat except for those patiets startig CPAP use i 1998 (p,0.001 for patiets startig durig the period of ; p for 1993). The curret authors were uable to explai the improvemet of the compliace by correlatig it to the baselie data (BMI, MAI, DI, CPAP, age, ad differece i MAI ad DI betwee the diagostic polysomography ad the sleep study uder CPAP), or by segregatig patiets ito two groups accordig to the media value of the variable. The evolutio of the compliace was ot explaied by chages i family or professioal status. The aswer rate from the telephoe FIGURE 1. Yearly compliace of 204 patiets versus time after cotiuous positive airway pressure (CPAP) oset. Data are preseted as mea SD. The umber of subjects studied each year was: years 1 5: 5204 each; year 6: 5176; year 7: 5134; year 8: 5112; year 9: 588; year 10: 567; year 11: 553; ad year 12: 527. : p, iterview was 88%. The ifluece of a chage of the CPAP device was also studied. Durig the study period, 96 patiets received a ew CPAP at a give time. They were well matched for MAI, DI, ad chage i MAI ad DI with the patiets remaiig o the first machie. The two groups showed the same developmet of mea compliace. Figure 3 shows the percetage of patiets startig CPAP therapy betwee 1996 ad 1998 ad followed-up util 2003 who quit treatmet. Betwee 1996 ad 1998, 154 patiets started CPAP. Of these, 35 (22.7%) abadoed treatmet (14.3, 3.2, 1.9, 1.3 ad 1.9% after 1, 2, 3, 4 ad 5 yrs, respectively). The compliace durig the first year of this group of patiets was statistically differet from compliace of those patiets still usig CPAP ( versus mi; p,0.001). There were also 11 deaths, eight objectively verified cures (DI f20 ad MAI f30), ad three withdrawals because the patiets were o loger covered by the social security for admiistrative reasos. Five patiets were lost at follow-up because they were trasferred to aother hospital. Therefore, out of 154 patiets startig CPAP, 60% were still usig the devices after 5 yrs. DISCUSSION I a cohort of patiets with moderate-to-severe obstructive sleep apoea surveyed for a log period, with follow-up ragig 5 12 yrs, it was foud that compliace to CPAP progressively ad statistically icreased over time with a average icrease of 8 mi?ight -1?yr -1. This is the first time, to the best of the curret authors kowledge, that this could be demostrated. As the study populatio remaied stable, patiets with low use rate who abadoed treatmet did ot ifluece the compliace that was obtaied. Moreover, the preset study demostrated that this evolutio was similar i the eight subgroups of patiets accordig to the year of recruitmet ito the study. The curret authors decided to make this stratificatio i order to verify that oe aual cohort did ot ifluece the results of the whole group. Ideed, all the ew patiets to whom CPAP was offered ad who started treatmet durig a give year showed the same evolutio ad, i almost all cases, the icrease of use with time was extremely sigificat from the statistical poit of view. The differece i compliace reached sigificace from the third year owards. These results cofirm previous data showig a stable compliace i a small subgroup of 36 patiets followed durig 3 yrs [5]. Accordig to the aalysis of the cohort icluded betwee 1996 ad 1998, 60% of these patiets used their devices for.5 yrs. This cohort is represetative of the whole populatio. It is ot kow whether such data are applicable to other settigs. I fact, there are o such data i the literature. The preset study is a first step ad others are ecessary to allow comparisos. Compliace to CPAP has bee show to be weakly correlated to baselie disease severity ad better to subjectively felt beefits [10]. Most of the previous studies were surveys of short duratio (moths or a few years). It has bee show previously that compliace after a mea follow-up of 784 days was correlated to baselie MAI (r50.226; p,0.05) [5]. I the preset study, oe of the cosidered baselie variables c EUROPEAN RESPIRATORY JOURNAL VOLUME 27 NUMBER 4 763

4 SLEEP APNOEA SYNDROME, CPAP AND COMPLIANCE M. SUCENA ET AL. a) b) c) 450 Compliace mi d) e) f) 450 Compliace mi g) h) Years after CPAP oset 450 Compliace mi Years after CPAP oset Years after CPAP oset FIGURE 2. Yearly compliace of each subgroup of patiets accordig to the year of iclusio i the study after cotiuous positive airway pressure (CPAP) oset from (a h, respectively). Data are preseted as mea SD. a, b, d g: p,0.001; c: p50.001; h: osigificat. (except CPAP pressure) correlated to compliace or to its evolutio with time. Recetly, LEWIS et al. [11] showed that compliace at 1 moth was ot correlated to baselie axiety, depressio scores, smokig or alcohol status, cocomitat pulmoary disease, or to the presece of a moustache or beard. Coversely, patiets experiecig o iitial tolerace problems to CPAP ad livig with a parter were better compliers [11]. To explai the icrease i compliace over time, a evetual chage i the family status was also explored. Sice this iformatio was ot available i the curret prospective data set, it was decided to perform telephoe iterviews of all the patiets i two selected subgroups where the icrease i compliace was without doubt (1994 ad 1996). Noe of the patiets had bee widowed, divorced or married durig the follow-up period. SIN et al. [12] showed that compliace at 6 moths was sigificatly correlated with female sex, reductio i a sleepiess score ad icreasig age. The mea compliace was 5.8 h at the ed of the study period ad was comparable to previous studies. I the study by SIN et al. [12], a 10-yr icremet i age was associated with a mea icrease of 15-mi CPAP use. I the preset logitudial study, it has bee show that the 10-yr icremet i CPAP use i a fixed group of patiets averaged 80 mi. If patiets used their CPAP more, this could be explaied by more time asleep. Retiremet is the best way to get more sleep hours i active patiets. I the same telephoe survey, the curret authors looked at this variable, but were ot able to demostrate, o a idividual basis, a lik of the icrease i CPAP use with the cessatio of the occupatioal career. The evetual ifluece of a chage i the CPAP device was studied, but i the etire study group. 764 VOLUME 27 NUMBER 4 EUROPEAN RESPIRATORY JOURNAL

5 M. SUCENA ET AL. SLEEP APNOEA SYNDROME, CPAP AND COMPLIANCE Abado % s l 1st l The most moder devices are smaller, lighter ad less oisy ad could, therefore, facilitate adherece. Patiets received a ew device whe the old oe became oisy or had a electroic failure. Whe comparig those patiets who received a ew device with those still usig the origial CPAP at the ed of the study period, o differece i mea compliace or i its evolutio was foud. Techological advaces i mask iterfaces would also be expected to improve compliace. Ideed, i the preset study populatio, masks were replaced almost every 1 2 yrs at the discretio of the patiet or the techical delegate who performed the yearly maiteace check. Ufortuately, this item was ot prospectively recorded i the study database. Nocompliace to CPAP is uderstadable. Wearig a CPAP device is all but coveiet. Air leaks, asal blockage or discharge, soreess, redess ad ulceratio of the ski, claustrophobia or aerophagy, ad oise are the most commo side-effects. A corrective measure ca be offered for the vast majority of side-effects. The oly oe for which o solutio exists is the sesatio of claustrophobia ad ivasiveess iduced by the mask, head girdle ad air pressure. May patiets quit or eve do ot start treatmet for this reaso. The acceptace rate reached 76% i the curret authors previous study [5]. It was ot determied i the preset oe. The quit rate oce treatmet was started was 11% i a previous study, i the rage foud by others. Parallel to this study, the preset authors re-examied this poit ad foud a quit rate of 22.7% after 5 yrs. It was more importat durig the first year (14.3%) ad was plateauig to a few per cet from the secod year. Other patiets may try to fid a compromise to the discomfort of CPAP. By usig it at a miimum level, it was foud to be sufficiet to couteract the deleterious effects of sleep apoea sydrome. This level sometimes lies below the miimal level imposed by the rules of the Belgia social security. I Belgium for istace, this level is set arbitrarily at 3 h?ight -1. I the preset study, 11 patiets used their CPAP,3 h durig the first year. All but oe patiet became ormal compliers at the ed of the study period, cotrary to the curret authors previous study, with a follow-up of 1 yr after a iitial survey s l 2d 3th 4th Year after the begiig of CPAP treatmet FIGURE 3. Rate of abadoig cotiuous positive airway pressure (CPAP) i patiets startig CPAP betwee 1996 ad : 1996; $: 1997; m: 1998; &: mea. s 5th of 2 yrs, where poor compliers (,3 h?day -1 ) remaied the same at 1 yr after the iitial survey. The preset data cofirm that early low compliace is a feature of patiets quittig treatmet i the first year of use. Moreover, most patiets who quit do so i the first year of treatmet. This suggests that reiforcig itervetios may be importat early after the itroductio of CPAP therapy, but that they are uecessary thereafter. Moreover MCARDLE et al. [13] studied 1,103 patiets with a media follow-up of 22 moths ad foud that compliace at 3 moths was strogly predictive of log-term use. If it is cosidered that, accordig to previous studies [4, 13], % of patiets eedig CPAP refuse the therapy ad that 20 [13] to 22.7% (curret data) of the patiets who start it will quit CPAP withi 5 yrs, the almost 60% of all patiets accept ad comply with therapy o very log-term follow-up [5, 13]. This is similar to what is foud i most other chroic diseases with the otable differece that compliace teds to decrease with time receivig therapy i these diseases [14]. 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