Split-Night Studies for the Diagnosis and Treatment of Sleep-Disordered Breathing

Sleep, 19(10):S255-S259 1996 American Sleep Disorders Association and Sleep Research Society Split-Night Studies for the Diagnosis and Treatment of Sleep-Disordered Breathing ". Patrick J. Strollo Jr., Mark H. Sanders, *Joseph P. Costantino, Sheila K. Walsh, Ronald A. Stiller and Charles W. Atwood, Jr. Division of Pulmonary, Allergy, and Critical Care Medicine, and *School of Public Health, University of Pittsburgh, University of Pittsburgh Medical Center, and The Pittsburgh Vetera Administration Medical Center, Pittsburgh, Penylvania, US.A Summary: We examined the effect of split-night polysomnography on compliance with positive pressure via a mask for the treatment of obstructive sleep-disordered breathing, A comparison of objective compliance (hours/day) at the first meter read from the positive-pressure device (4-6 weeks after set-up) in patients who had a successful split-night positive-pressure titration vs. patients who had traditional full-night positive-pressure titration was performed. Patients were matched for age, sex, and severity of the obstructive sleep-disordered breathing. Twelve patients were matched with controls who underwent full-night polysomnography. There were no significant differences between the split-night patients and the full-night patients with regard to age, sex, body mass index, and pretreatment Epworth Sleepiness Score. In addition, there was no significant difference between apnea-hypopnea index and the desaturation-event frequency for both groups pre- and post-treatment. The average daily use of continuous positive airway pressure (CPAP) at the time of the first meter reading in the group that underwent full-night positivepressure titratio as opposed to split-night titratio was 5.2 hours/day ± 2.2 vs. 3.8 hours/day ± 2.9, respectively (p = 0.29). The Epworth Sleepiness Scale on the initial clinic visit (as an index of patient-perceived impairment) did not predict compliance at 4-6 weeks. The time at the final positive pressure did not correlate with compliance. Acceptance of positive pressure in the split-night patients ranged from 62 to 67%. Key Words: Sleep studies Obstructive sleep apnea-split-night studies-treatment-acceptance-compliance. We have previously reported that a partial-night study is sufficient to diagnose obstructive sleep apnea (OSA) (I). Additional studies by our group and others have demotrated that an effective positive-pressure prescription can be achieved in 60% to 80% of patients with obstructive sleep-disordered breathing (2,3). On the basis of this work and personal experience, many sleep centers have adopted protocols that involve splitnight polysomnography. These protocols have been employed in an effort to expedite treatment, maximize resource utilization, and contain cost. It is recognized that, although safe and effective in maintaining upperairway patency during sleep, the primary drawback of positive-pressure therapy is its volitional nature requiring that the patient actively participate in the treatment process. Patient compliance with treatment is all too often sub-optimal, even after a traditional fullnight positive-pressure titration in an attended laboratory environment. It is, therefore, relevant to question Accepted for publication October 1996. Address correspondence and reprint requests to Patrick Strollo, Division of Pulmonary-Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, U.S.A. S255 if split-night polysomnography negatively impacts on patient acceptance and compliance with positive-pressure therapy. Jamieson (4) has recently admonished that, although establishing a proper positive-pressure prescription is for the most part an immediate and objectively measured task, providing education and orientation to the patient to facilitate compliance reflect more time-couming and interpersonal efforts that may not be optimized in the confines of a split-night study (4). We have had similar concer regarding the adequacy of split-night polysomnography as a primary approach to the diagnosis and to initiating treatment for patients with obstructive sleep-disordered breathing. As we have learned more about sleep-related breathing disturbances from the standpoint of both identification and measurement of physiologically significant events, this concern has been heightened (5-8). Positive pressure via a mask is the initial treatment of choice for obstructive sleep-disordered breathing (9). Modifying laboratory practices in the way that obstructive sleepdisordered breathing is diagnosed and therapy is initiated to contain short-term costs and increase avail-

ability of medical care may prove more costly and detrimental to medical care in the long run if acceptance and compliance with prescribed treatment is adversely influenced. To date, no controlled studies have examined the effect of a split-night protocol on patient acceptance and compliance with positive-pressure therapy. The following data represents our initial exploratory effort to address this issue. METHODS A retrospective, case-controlled chart review was utilized to examine the effect of split-night polysomnography on compliance with positive pressure via a mask. Patients referred to the University of Pittsburgh Pulmonary Sleep Evaluation Center (PSEC) for the diagnosis and treatment of suspected obstructive sleep apnea (OSA) from September 1994 to September 1995 were eligible for the study. All patients underwent a complete history and physical examination by one of the physician staff members of the PSEC prior to polysomnography. An Epworth Sleepiness Score was recorded for all patients (10). The decision to utilize split-night methodology as opposed to full-night diagnostic polysomnography followed by a full-night therapeutic trial was a function of the PSEC physician's perception of the clinical urgency and availability of laboratory resources. An element of bias toward or agait the utility of split-night studies could not be excluded. Polysomnography was performed in a standard fashion. Sleep and breathing data were collected and scored as previously reported (2). Patients undergoing split-night studies underwent a positive-pressure titration if >30 apneas or hypopneas were observed by the technician in attendance. Patients were allowed to try breathing with a variety of commercially available masks prior to the study. The masks were changed and a chin strap was added (if required) during the titration in order to optimize the mask fit and to overcome any mask leaks that developed. Continuous positive airway pressure (CPAP) was increased in 2.5 cm H 2 0 increments in order to abolish all obstructive apneas, hypopneas, and snoring. Patients were changed to a bi-level positive-pressure system if the patient complained of inability to exhale on CPAP or if maximal CPAP was unable to adequately correct the sleep-related breathing disturbance. A study was not coidered adequate unless rapid eye movement (REM) sleep was recorded at the final pressure. A comparison of objective compliance (average number of hours/day) at the first meter reading (4-6 weeks after the patient received the positive-pressure device) in patients who had a successful split-night titration and who had accepted therapy (defined as Patient Selection: Split Nights «72 Patients p,eo;.u! stud ~ 5 2.1 8 Not OSA study/i" \\ 5 no FlU 15 Refused Rx 3 Split to 02 25 Patients '\... 6 No meter re~ t 7 No match 12 Matched with Controls FIG. 1. Graphical representation of how patients who underwent split-night polysomnography were selected for analysis. agreeing to InItIate treatment) was compared to matched patients who had a full-night-attended positive-pressure titration and who had accepted therapy. The patients who underwent split-night studies were matched for age, sex, and severity of obstructive sleepdisordered breathing with patients who underwent conventional 2 night diagnostic and therapeutic studies. During the study period, 72 patients underwent split-night polysomnography. The patient selection strategy is shown in Fig. 1. Of the 72 patients studied with split-night polysomnography, 24 patients either had a previous study (five patients), required a second night due to inability to achieve a satisfactory positivepressure prescription (11 patients), or did not have obstructive sleep apnea (eight patients). Three patients were "split" to an oxygen titration and five patients were lost to follow-up. Six patients did not have a meter reading available after initiation of treatment and no matched-control subjects were available for seven patients. Fifteen patients who underwent split-night polysomnography refused positive-pressure therapy. As a result of the above exclusio, 12 patients who underwent split-night polysomnography were included in this analysis. Twelve matched controls who underwent full-night-attended diagnostic and therapeutic polysomnograms were identified. The patient data were analyzed with a paired t test and the McNemar's test. All values are expressed as the mean ± standard deviation. Significance was determined as p :5 0.05. RESULTS The demographic and respiratory sleep data are shown in Table 1. There were no significant differences between the split-night patients and the fullnight patients with regard to age, sex, body mass index (BMI), and pre-treatment Epworth Sleepiness Score. l I I S256 P.l. STROLLO ET AL.

.. SPLIT NIGHT STUDIES S257 TABLE 1. Demographic and sleep data Split night (n = 12) Full night (n = 12) Split Night Studies: Time at Final Pressure (minutes) vs Compliance (hours/day) 300 R 2 = 0.01., Demographic data: Age MIF BMI Epworth CPAPlbi-level 44.4 ± 14.4 8/4 40.7 ± 11.4 13.6 ± 4.8 10/2 44.3 ± 14.4 8/4 36.0 ± 5.8 12.0 ± 4.9 1111 Sleep-disordered breathing data (diagnostic): AHI 27.1 ± 40.6 27.2 ± 40.1 DEF" 22.7 ± 20.0 23.3 ± 21.6 Sleep-disordered breathing data (therapeutic): AHI 10.9 ± 9.1 7.4 ± 7.1 DEF" 1.2 ± 1.1 1.0 ± 0.7 a 25% desaturatio from baseline per hour of sleep. Minutes 200 100 a a 2 4 Hours I Day FIG. 2. Graph demotrating the correlation between the time at the final positive pressure during the split-night titration and the objective compliance in mean hours per day of use.,. In addition, there was no significant difference between apnea-hypopnea index (AHI), and the desaturation-event frequency (DEF) for both groups pre- and post-treatment. In the split-night group, 10 patients were prescribed CP AP and two patients were prescribed bi-level pressure devices. In the full-night group, 11 patients were prescribed CPAP and one patient was prescribed a bi-level pressure system. Although not statistically significant, there was a trend toward an increase in the average daily use of CPAP at the time of the first meter reading in the group that underwent full-night positive-pressure titratio as opposed to split-night titratio: 5.2 hours/day ± 2.2 vs. 3.8 hours/day ± 2.9, respectively (p = 0.29). The pre-treatment Epworth Sleepiness Score did not predict compliance with positive pressure in either the split-night or full-night patient groups. The duration of administration of the final positive pressure level in the split-night group did not correlate with compliance (Fig. 2). The mean time at the final positive pressure was 72.5 ± 103.6 minutes (range: 20-243 minutes). There was no significant difference in the final level of CPAP between the two groups: split night 9.8 ± 4.0 cm H 2 0 vs. full night 10.4 ± 3.5 cm HP (p = 0.73). Two patients in whom positive pressure was introduced in a split night were prescribed bi-level pressure (15 cm H 2 0/lO cm H 2 0 and 15 cm H 2 0/5 cm H 2 0, respectively). One patient in whom positive pressure was introduced in a full night was prescribed bi-level pressure (10 cm H 2 012.5 cm H 2 0). There was no correlation between the AHI on the diagnostic study vs. compliance in the split-night group (r 2 == 0.00) and a weak: correlation in the fullnight group (r2 = 0.16). We also assessed acceptance of positive-pressure therapy in patients who underwent split-night polysomnography. Of the 72 patients studied with splitnight polysomnography, 40 were clearly available for analysis following split-night polysomnography (Fig. 1), and if one includes the five patients who were lost to follow-up in the analysis, the total would be 45 patients. Analyzing only the 40 patients about whom no assumptio were made regarding acceptance, the acceptance rate was then 62.5% (25/40 patients accepting therapy). If the additional five patients who were lost to follow-up are included, and it is assumed that they accepted positive-pressure therapy, the overall acceptance was 67% (30/45 patients). Fifteen percent of the patients ( 11172 patients) required a second night of study to determine an adequate positive-pressure prescription. DISCUSSION Our results indicate the following: (1) At 4-6 weeks following initiation of positive-pressure therapy, patients who underwent split-night positive-pressure titratio had a mean compliance (hours/day) that was not statistically different from a group of well-matched controls who underwent full-night positive pressure titratio. (2) The Epworth Sleepiness Scale on the initial clinic visit (as an index of patient perceived impairment) did not predict compliance at 4-6 weeks. (3) The time at the final positive pressure did not correlate with compliance. We also observed that patient acceptance of therapy (defined as willingness to initiate treatment) was lower after a split-night titration than compared with previously reported acceptance rates that varied between 72% and 92% after full-night titratio (Table 2) (11-13). Fleury et al. (14) recently reported an uncontrolled prospective case series in which 31 patients with moderate-to-severe OSA (AHI == 66 ± 23) underwent split-night polysomnography. Thirteen percent of the patients (4/31 patients) had an inadequate

S258 P. J. STROLLO ET AL. TABLE 2. Positive-pressure therapy Split-night polysomnograms Strollo et al. a Fleury et al. (14) Full-night polysomnograms Rauscher et al. (13) Krieger (12) Hoffstein et al. (11) a Current study. Positive pressure acceptance Acceptance 62-67% 75% 72% 92% 71-76% CPAP titration, as compared to 15% (11172 patients) in our split-night group. Yamashiro and Kryger (15) have previously reported that in patients undergoing split-night titratio, the CPAP prescription may be inaccurate when the AHI is <20. Our study did not address the precision of the positive-pressure prescription on the basis of a split night as opposed to a full night. However, there was no significant correlation with compliance and severity of obstructed sleep-disordered breathing as reflected by the AHI in the split night (,-2 = 0.01) or full night (r 2 = 0.005) groups. In the study by Fleury et al. (14), 75% (21128) of the patients accepted CPAP therapy. Our acceptance data was lower at 62-67%. This may have been influenced by the fact that our population had lower AHI as a group compared to the AHI in the Fleury study: 27.1 ± 40.6 vs. 63.6 ± 20.5. Rauscher et al. (13) found that in patients who underwent full-night titratio, acceptance correlated strongly with the severity of obstructed sleep-disordered breathing (13). Krieger (12) and Hoffstien et al. (11) did not formally examine the relatiohip between AHI and acceptance in patients who underwent full-night titratio. Interpretation of our results must be tempered by the fact that the study group was small. We performed a power calculation to determine the number of patients required to detect a statistically significant difference of 1 hour in compliance between the two groups with a 95% level of confidence (alpha = 0.05). The calculation indicated that 160 patients would be required in each of the split-night and full-night groups. All the patients were seen in coultation by a sleep specialist prior to polysomnography. Patient education regarding the diagnosis and treatment of OSA was provided by the sleep specialist. The effect of "by-passing" the sleep specialist in the diagnosis and treatment of obstructive sleep-disordered breathing has not been studied. This is relevant because, at the present time, physician education in sleep medicine is inadequate (16). If patient management decisio regarding polysomnography are relegated solely to primary-care physicia, it is conceivable that acceptance and compliance of positive therapy could be negatively affected in a more profound manner. In summary, utilizing split-night protocols to diagnose and initiate treatment for OSA has the promise of being more expeditious and cost effective. However, concern exists that providing less than a full night for introducing positive-pressure therapy may be deleterious to patient acceptance and compliance and, if so, may result in patients choosing less effective surgical interventio or refusing any treatment. Further work is required to define what patient subsets are suitable for split-night polysomnography. Clinical experience suggests that patients with severe OSA may do well with a split-night protocol; however, no prospective, controlled studies with measurement of objective compliance have been conducted to support this notion. Although the initial therapeutic intervention of choice, treatment with positive pressure via a mask is clearly unique (17). Successful positive-pressure treatment utilizing split-night or full-night polysomnography that is either home or sleep-center based will mandate that protocols for patient education and compliance be developed, standardized, and tested with appropriate scientific rigor. 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