The Development of a Novel mHealth Tool for Obstructive Sleep Apnea: Tracking Continuous Positive Airway Pressure Adherence as a Percentage of Time in Bed

BACKGROUND

Continuous positive airway pressure (CPAP) is the mainstay obstructive sleep apnea (OSA) treatment; however, poor adherence to CPAP is common. Current guidelines specify 4 hours of CPAP use per night as a target to define adequate treatment adherence. However, effective OSA treatment requires CPAP use during the entire time spent in bed to optimally treat respiratory events and prevent adverse health effects associated with the time spent sleeping without wearing a CPAP device. Nightly sleep patterns vary considerably, making it necessary to measure CPAP adherence relative to the time spent in bed. Weight loss is an important goal for patients with OSA. Tools are required to address these clinical challenges in patients with OSA.

OBJECTIVE

This study aimed to develop a mobile health tool that combined weight loss features with novel CPAP adherence tracking (ie, percentage of CPAP wear time relative to objectively assessed time spent in bed) for patients with OSA.

METHODS

We used an iterative, user-centered process to design a new CPAP adherence tracking module that integrated with an existing weight loss app. A total of 37 patients with OSA aged 20 to 65 years were recruited. In phase 1, patients with OSA who were receiving CPAP treatment (n=7) tested the weight loss app to track nutrition, activity, and weight for 10 days. Participants completed a usability and acceptability survey. In phase 2, patients with OSA who were receiving CPAP treatment (n=21) completed a web-based survey about their interpretations and preferences for wireframes of the CPAP tracking module. In phase 3, patients with recently diagnosed OSA who were CPAP naive (n=9) were prescribed a CPAP device (ResMed AirSense10 AutoSet) and tested the integrated app for 3 to 4 weeks. Participants completed a usability survey and provided feedback.

RESULTS

During phase 1, participants found the app to be mostly easy to use, except for some difficulty searching for specific foods. All participants found the connected devices (Fitbit activity tracker and Fitbit Aria scale) easy to use and helpful. During phase 2, participants correctly interpreted CPAP adherence success, expressed as percentage of wear time relative to time spent in bed, and preferred seeing a clearly stated percentage goal ("Goal: 100%"). In phase 3, participants found the integrated app easy to use and requested push notification reminders to wear CPAP before bedtime and to sync Fitbit in the morning.

CONCLUSIONS

We developed a mobile health tool that integrated a new CPAP adherence tracking module into an existing weight loss app. Novel features included addressing OSA-obesity comorbidity, CPAP adherence tracking via percentage of CPAP wear time relative to objectively assessed time spent in bed, and push notifications to foster adherence. Future research on the effectiveness of this tool in improving OSA treatment adherence is warranted.

68 Outcomes of Emergency Appendicectomy At Torbay Hospital During Peak SARS-COV-2 Pandemic

Introduction

SARS-COV-2 has created unprecedented challenges for healthcare systems. As a result, new intercollegiate guidelines have been published in the UK to manage emergency surgeries commencing 25th March 2020. Devon has one of the lowest incidences of Covid-19 in UK. In this study, we report outcomes of emergency appendicectomy at Torbay Hospital during peak COVID-19 pandemic, from 25th March till 26th May 2020.

Method

This is a single centre retrospective review at Torbay Hospital, Devon. It includes all patients who underwent emergency appendicectomy. Primary outcomes were intra-operative findings, change of operation choice due to revised guidelines, and length of admission. The secondary outcome was 14 days post-operative mortality and morbidity.

Results

A total of 29 patients, median age 33.1, underwent emergency appendicectomy. 79.3% (n = 23) had a pre-operative SARS-COV-2 nasal swab test, all of which were negative. All appendicectomies were conducted in a non-COVID theatre. Level 3 PPE and precautions were used intra-operatively. The choice of operation was changed in 37.9% (n = 10), from laparoscopic to open as per COVID-19 guidelines. Most patients (86.2%) were discharged from hospital within 5 days of operation. None of the patients or surgeons contracted COVID-19 related infection in 14 days following the operation.

Conclusions

This study is a snapshot into safety of operative management of acute appendicitis in patients not suspected of COVID-19 infection during first wave of pandemic. However, it will be interesting to see long-term multi-centre comparative studies analysing the effect of surgical management of appendicitis during all three waves of pandemic.

Optimal Continuous Positive Airway Pressure Treatment of Obstructive Sleep Apnea Reduces Daytime Resting Heart Rate in Prediabetes: A Randomized Controlled Study

Background It has been widely recognized that obstructive sleep apnea (OSA) is linked to cardiovascular disease. Yet, randomized controlled studies failed to demonstrate a clear cardiovascular benefit from OSA treatment, mainly because of poor adherence to continuous positive airway pressure (CPAP). To date, no prior study has assessed the effect of CPAP treatment on daytime resting heart rate, a strong predictor of adverse cardiovascular outcomes and mortality. Methods and Results We conducted a randomized controlled study in 39 participants with OSA and prediabetes, who received either in-laboratory all-night (ie, optimal) CPAP or an oral placebo for 2 weeks. During daytime, participants continued daily activities outside the laboratory. Resting heart rate was continuously assessed over 19 consecutive days and nights using an ambulatory device consisting of a single-lead ECG and triaxis accelerometer. Compared with placebo, CPAP reduced daytime resting heart rate (treatment difference, -4.1 beats/min; 95% CI, -6.5 to -1.7 beats/min; P=0.002). The magnitude of reduction in daytime resting heart rate after treatment significantly correlated with the magnitude of decrease in plasma norepinephrine, a marker of sympathetic activity (r=0.44; P=0.02), and the magnitude of decrease in OSA severity (ie, apnea-hypopnea index [r=0.48; P=0.005], oxygen desaturation index [r=0.50; P=0.003], and microarousal index [r=0.57; P<0.001]). Conclusions This proof-of-concept randomized controlled study demonstrates, for the first time, that CPAP treatment, when optimally used at night, reduces resting heart rate during the day, and therefore has positive cardiovascular carry over effects. These findings suggest that better identification and treatment of OSA may have important clinical implications for cardiovascular disease prevention. Registration URL: https:/// www.clini​caltr​ials.gov; Unique identifier: NCT01156116.

MON-034 Impact of Race and Obstructive Sleep Apnea on Glucose and Insulin Regulation in Women with PCOS

The prevalence of prediabetes and diabetes is substantially higher in PCOS women with obstructive sleep apnea (OSA) compared to PCOS women without OSA1,2,3. Prior studies, however, did not examine the complex interaction between race and OSA on metabolic function in PCOS. We sought to determine if the impact of OSA on glucose and insulin metabolism is affected by race. We studied non-Hispanic white (NHW) (n=53) and African-American (AA) (n=48) women with PCOS. Following an overnight polysomnogram (PSG), PCOS women (NHW without OSA n=40; NHW with OSA n=13; AA without OSA n=36; AA with OSA n=12) had a 2-h 75-g oral glucose tolerance test (OGTT) with blood sampling every 30 minutes for measurement of glucose, insulin, and C-peptide concentrations. OSA severity was measured by the Apnea-Hypopnea Index (AHI). Only women without OSA (AHI &lt; 5) or with moderate-to-severe OSA (AHI &gt; 15) were included in these analyses; women with mild OSA were excluded. Insulin secretion rates (ISR) during the OGTT were derived by deconvolution of C-peptide levels 4. Area under the curve (AUC) response to the glucose challenge was calculated using the trapezoidal method. BMI and age did not differ between races in PCOS women without OSA (BMI [kg/m2]: 36.3±1.2 vs. 37.2±1.1, p=0.58; Age [yr]: 27.7±0.8 vs. 27.2±0.8, p=0.65; for NHW and AA respectively), or in PCOS women with OSA (BMI [kg/m2]: 42.8±1.7 vs. 44.7±2.0, p=0.50; Age [yr]: 31.4±1.6 vs. 28.6±1.6, p=0.18; for NHW and AA respectively). OSA severity was similar in NHW and AA PCOS women without OSA (AHI: 1.5±0.2 vs 2.1±0.2, p=0.076), and PCOS women with OSA (AHI: 32.0±4.9 vs. 28.3±4.4, p=0.26). Higher glucose responses during the OGTT were observed in NHW PCOS women with OSA compared to both NHW (AUC: 18,965±648 vs. 15,797±371, p=0.0004) and AA (AUC: 18,965±648 vs. 15,801±497, p=0.0005) PCOS women without OSA. Glucose responses did not differ significantly between AA PCOS women with OSA and AA PCOS women without OSA (AUC: 17,104±965 vs. 15,801±497, p=0.15). Similarly, ISR was higher in NHW PCOS women with OSA compared to both NHW (AUC: 5,648±488 vs. 3,907±231, p=0.0006) and AA (AUC: 5,648±488 vs. 3,981±235, p=0.0011) PCOS women without OSA. ISR did not differ significantly between AA PCOS women with OSA and AA PCOS women without OSA (AUC: 4,827±461 vs. 3,981±235, p=0.09). CONCLUSIONS: OSA has a greater impact on glucose and ISR during an oral glucose challenge in NHW compared to AA women with PCOS. Future studies would benefit from including race when evaluating metabolic outcomes in women with PCOS. References: 1Fogel et al., J Clin Endocrinol Metab. 2001: 86:1175–1180. 2Kapsimalis et al., Sleep. 2002; 25:499–506. 3Kapsimalis et al., Sleep. 2002; 25:412–419. 4Polonsky et al., J Clin Invest. 1986 Jan; 77(1):98–105.

Apnea-hypopnea index, nocturnal arousals, oxygen desaturation and structural brain changes: A population-based study

Sleep apnea has been related to brain changes such as atrophy. However, which component of sleep apnea, the apnea-hypopnea index (AHI), nocturnal oxygen desaturation or arousals, can explain this association is unclear. In this large population-based study (n=681, mean age 62.1 years), we investigated the associations of AHI, nocturnal oxygen desaturation and arousals with global and regional gray matter and white matter volumes and with white matter lesion volumes. All participants underwent one night of polysomnography and MRI scanning of their brain. Gray matter, white matter and white matter lesion volumes adjusted for intracranial volume were studied as markers of brain atrophy. Nocturnal oxygen desaturation was related to whole brain white matter atrophy independent of covariates (multivariable adjusted B=−8.3, 95% CI=−16.7; −0.02). This association was most prominently reflected in the association between more oxygen desaturation and a smaller white matter parietal volume (B=−3.95 ml, 95% CI=−6.02; −1.88). Furthermore, oxygen desaturation was related to a smaller hippocampus (B=−0.22 ml, 95% CI=−0.42; −0.01). Although a higher AHI was related to smaller parietal gray (B=−0.05, 95% CI=−0.09; −0.004) and white matter (B=−0.06, 95% CI=−0.12; −0.10) volumes, these associations disappeared when adding oxygen desaturation to the model. We did not find a relation between arousals and gray and white matter brain atrophy and white matter lesion volumes. This suggests that oxygen desaturation mainly explains the association between sleep apnea and brain damage.

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Nocturnal oxygen desaturation is associated with a smaller white matter volume.

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A higher AHI is related to smaller parietal gray and white matter volumes.

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These associations disappear when adding oxygen desaturation to the model.

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Oxygen desaturation mainly explains the association between apnea and brain damage.

Eight Hours of Nightly Continuous Positive Airway Pressure Treatment of Obstructive Sleep Apnea Improves Glucose Metabolism in Patients with Prediabetes. A Randomized Controlled Trial

RATIONALE

Although obstructive sleep apnea (OSA) is associated with impaired glucose tolerance and diabetes, it remains unclear whether OSA treatment with continuous positive airway pressure (CPAP) has metabolic benefits.

OBJECTIVES

To determine the effect of 8-hour nightly CPAP treatment on glucose metabolism in individuals with prediabetes and OSA.

METHODS

In a randomized controlled parallel group study, 39 participants were randomly assigned to receive either 8-hour nightly CPAP (n = 26) or oral placebo (n = 13). Sleep was polysomnographically recorded in the laboratory on each night. CPAP adherence was ensured by continuous supervision. Participants continued their daily routine activities outside the laboratory. Glucose metabolism was assessed at baseline and after 2 weeks of assigned treatment using both the oral and intravenous glucose tolerance tests. The primary outcome was the overall glucose response as quantified by the area under the curve for glucose during 2-hour oral glucose tolerance testing. Secondary outcomes included fasting and 2-hour glucose and insulin, the area under the curves for insulin and insulin secretion, norepinephrine, insulin sensitivity, acute insulin response to glucose, and 24-hour blood pressure.

MEASUREMENTS AND MAIN RESULTS

The overall glucose response was reduced (treatment difference: -1,276.9 [mg/dl] · min [95% confidence interval, -2,392.4 to -161.5]; P = 0.03) and insulin sensitivity was improved (treatment difference: 0.77 [mU/L](-1) · min(-1) [95% confidence interval, 0.03-1.52]; P = 0.04) with CPAP as compared with placebo. Additionally, norepinephrine levels and 24-hour blood pressure were reduced with CPAP as compared with placebo.

CONCLUSIONS

In patients with prediabetes, 8-hour nightly CPAP treatment for 2 weeks improves glucose metabolism compared with placebo. Thus, CPAP treatment may be beneficial for metabolic risk reduction. Clinical trial registered with www.clinicaltrials.gov (NCT 01156116).

Temporal disorganization of circadian rhythmicity and sleep-wake regulation in mechanically ventilated patients receiving continuous intravenous sedation

OBJECTIVES

Sleep is regulated by circadian and homeostatic processes and is highly organized temporally. Our study was designed to determine whether this organization is preserved in patients receiving mechanical ventilation (MV) and intravenous sedation.

DESIGN

Observational study.

SETTING

Academic medical intensive care unit.

PATIENTS

Critically ill patients receiving MV and intravenous sedation.

METHODS

Continuous polysomnography (PSG) was initiated an average of 2.0 (1.0, 3.0) days after ICU admission and continued ≥ 36 h or until the patient was extubated. Sleep staging and power spectral analysis were performed using standard approaches. We also calculated the electroencephalography spectral edge frequency 95% SEF₉₅, a parameter that is normally higher during wakefulness than during sleep. Circadian rhythmicity was assessed in 16 subjects through the measurement of aMT6s in urine samples collected hourly for 24-48 hours. Light intensity at the head of the bed was measured continuously.

MEASUREMENTS AND RESULTS

We analyzed 819.7 h of PSG recordings from 21 subjects. REM sleep was identified in only 2/21 subjects. Slow wave activity lacked the normal diurnal and ultradian periodicity and homeostatic decline found in healthy adults. In nearly all patients, SEF₉₅ was consistently low without evidence of diurnal rhythmicity (median 6.3 [5.3, 7.8] Hz, n = 18). A circadian rhythm of aMT6s excretion was present in most (13/16, 81.3%) patients, but only 4 subjects had normal timing. Comparison of the SEF₉₅ during the melatonin-based biological night and day revealed no difference between the 2 periods (P = 0.64).

CONCLUSIONS

The circadian rhythms and PSG of patients receiving mechanical ventilation and intravenous sedation exhibit pronounced temporal disorganization. The finding that most subjects exhibited preserved, but phase delayed, excretion of aMT6s suggests that the circadian pacemaker of such patients may be free-running.

Automated detection of sleep EEG slow waves based on matching pursuit using a restricted dictionary

In this paper, an original method to detect sleep slow waves (SSW) in electroencephalogram (EEG) recordings is proposed. This method takes advantage of a Matching Pursuit algorithm using a dictionary reduced to Gabor functions reproducing the main targeted waveform characteristics. By describing the EEG signals in terms of SSW properties, the corresponding algorithm is able to identify waveforms based on the largest matching coefficients. The implemented algorithm was tested on a database of whole night sleep EEG recordings collected in 9 young healthy subjects where SSW have been visually scored by an expert. Besides being fully automated and much faster than visual scoring analysis, the results obtained to the proposed method were in excellent agreement with the expert with 98% of correct detections and a 77% concordance in event time position and duration. These results were superior from those of the classical method both in terms of sensibility and precision.

Changes in insulin secretion and action in adults with familial risk for type 2 diabetes who curtail their sleep

OBJECTIVE

Experimental sleep deprivation is accompanied by changes in glucose regulation. However, the effects of chronic sleep insufficiency on insulin secretion and action in populations at high risk for type 2 diabetes are not known. This study examined the relationship between objectively documented habitual sleep curtailment and measures of insulin sensitivity, insulin secretion, and oral glucose tolerance in free-living adults with parental history of type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 47 healthy participants with parental history of type 2 diabetes (26 female/21 male, mean [SD] age 26 [4] years and BMI 23.8 [2.5] kg/m(2)) completed 13 (SD = 2) days of sleep and physical activity monitoring by wrist actigraphy and waist accelerometry while following their usual lifestyle at home. Laboratory polysomnography was used to screen for sleep disorders. Indices of diabetes risk based on oral glucose tolerance tests were compared between participants with habitual short sleep and those with usual sleep duration >6 h/day.

RESULTS

Consistent with a behavioral pattern of habitual sleep curtailment, short sleepers obtained an average of 1.5 h less sleep per night and showed signs of increased sleep pressure. Participants who habitually curtailed their sleep had considerably higher indices of insulin resistance and increased insulin secretion but maintained normal glucose tolerance similar to that of subjects who slept more.

CONCLUSIONS

Young lean adults with parental history of type 2 diabetes who habitually curtail their sleep have increased insulin resistance and compensatory hyperinsulinemia--a pattern that has been associated with higher risk of developing diabetes in such susceptible individuals.

Treatment of obstructive sleep apnea improves cardiometabolic function in young obese women with polycystic ovary syndrome

CONTEXT

Women with polycystic ovary syndrome (PCOS) are insulin resistant and have a high risk of early-onset diabetes and cardiovascular disease. Obstructive sleep apnea (OSA) has adverse cardiometabolic consequences and is highly prevalent in women with PCOS. We sought to determine whether continuous positive airway pressure (CPAP) treatment of OSA has beneficial effects on cardiometabolic function in PCOS.

METHODS

Laboratory polysomnography and cardiometabolic measurements including insulin sensitivity and secretion (iv glucose tolerance test); 24-h profiles of plasma catecholamines, cortisol, and leptin; and daytime profiles of blood pressure and cardiac autonomic activity (heart rate variability) were obtained at baseline and again after 8 wk of home CPAP treatment with daily usage monitoring.

RESULTS

CPAP treatment modestly improved insulin sensitivity after controlling for body mass index (P = 0.013). The change in insulin sensitivity correlated positively with CPAP use (adjusted P = 0.027) and negatively with body mass index (adjusted P = 0.003). Daytime and nighttime norepinephrine levels were decreased after CPAP (P = 0.002), and the reductions were greater with increased CPAP use (P = 0.03). Epinephrine, cortisol, and leptin levels were not changed significantly. Daytime diastolic blood pressure decreased by an average of 2.3 mm Hg after CPAP (P = 0.035). Cardiac sympathovagal balance was 44% lower (P = 0.007) after CPAP, reflecting a shift toward lower sympathetic activity.

CONCLUSIONS

In young obese women with PCOS, successful treatment of OSA improves insulin sensitivity, decreases sympathetic output, and reduces diastolic blood pressure. The magnitude of these beneficial effects is modulated by the hours of CPAP use and the degree of obesity.

Impact of untreated obstructive sleep apnea on glucose control in type 2 diabetes

RATIONALE

Obstructive sleep apnea (OSA), a treatable sleep disorder that is associated with alterations in glucose metabolism in individuals without diabetes, is a highly prevalent comorbidity of type 2 diabetes. However, it is not known whether the severity of OSA is a predictor of glycemic control in patients with diabetes.

OBJECTIVES

To determine the impact of OSA on hemoglobin A1c (HbA1c), the major clinical indicator of glycemic control, in patients with type 2 diabetes.

METHODS

We performed polysomnography studies and measured HbA1c in 60 consecutive patients with diabetes recruited from outpatient clinics between February 2007 and August 2009.

MEASUREMENTS AND MAIN RESULTS

A total of 77% of patients with diabetes had OSA (apnea-hypopnea index [AHI] > or =5). Increasing OSA severity was associated with poorer glucose control, after controlling for age, sex, race, body mass index, number of diabetes medications, level of exercise, years of diabetes and total sleep time. Compared with patients without OSA, the adjusted mean HbA1c was increased by 1.49% (P = 0.0028) in patients with mild OSA, 1.93% (P = 0.0033) in patients with moderate OSA, and 3.69% (P < 0.0001) in patients with severe OSA (P < 0.0001 for linear trend). Measures of OSA severity, including total AHI (P = 0.004), rapid eye movement AHI (P = 0.005), and the oxygen desaturation index during total and rapid eye movement sleep (P = 0.005 and P = 0.008, respectively) were positively correlated with increasing HbA1c levels.

CONCLUSIONS

In patients with type 2 diabetes, increasing severity of OSA is associated with poorer glucose control, independent of adiposity and other confounders, with effect sizes comparable to those of widely used hypoglycemic drugs.

Validation of high-throughput methods for measuring blood urea nitrogen and urinary albumin concentrations in mice

Chronic kidney disease is a substantial medical and economic burden. Animal models, including mice, are a crucial component of kidney disease research; however, recent studies disprove the ability of autoanalyzer methods to accurately quantify plasma creatinine levels, an established marker of kidney disease, in mice. Therefore, we validated autoanalyzer methods for measuring blood urea nitrogen (BUN) and urinary albumin concentrations, 2 common markers of kidney disease, in samples from mice. We used high-performance liquid chromatography to validate BUN concentrations measured using an autoanalyzer, and we utilized mouse albumin standards to determine the accuracy of the autoanalyzer over a wide range of albumin concentrations. We observed a significant, linear correlation between BUN concentrations measured by autoanalyzer and high-performance liquid chromatography. We also found a linear relationship between known and measured albumin concentrations, although the autoanalyzer method underestimated the known amount of albumin by 3.5- to 4-fold. We confirmed that plasma and urine constituents do not interfere with the autoanalyzer methods for measuring BUN and urinary albumin concentrations. In addition, we verified BUN and albuminuria as useful markers to detect kidney disease in aged mice and mice with 5/6-nephrectomy. We conclude that autoanalyzer methods are suitable for high-throughput analysis of BUN and albumin concentrations in mice. The autoanalyzer accurately quantifies BUN concentrations in mouse plasma samples and is useful for measuring urinary albumin concentrations when used with mouse albumin standards.

Job-based health insurance in 2001: inflation hits double digits, managed care retreats

Drawing on the results of a national survey of 1,907 firms with three or more workers, this paper reports on several facets of job-based health insurance, including the cost to employers and workers; plan offerings and enrollments; patient cost sharing and benefits; eligibility, coverage, and take-up rates; and results from questions about employers' knowledge of market trends and health policy initiatives. Premiums increased 11 percent from spring 2000 to spring 2001, and the percentage of Americans in health maintenance organizations (HMOs) fell six percentage points to its lowest level since 1993, while preferred provider organization (PPO) enrollment rose to 48 percent. Despite premium increases, the percentage of firms offering coverage remained statistically unchanged, and a relatively strong labor market has continued to shield workers from the higher cost of coverage.

Fine mapping of Ath6, a quantitative trait locus for atherosclerosis in mice

Ath6 is a novel quantitative trait locus associated with differences in susceptibility to atherosclerosis between C57BL/6J (B6) and C57BLKS/J (BKS) inbred mouse strains. Combining data from an intercross and a backcross (1593 meioses) between mice from B6 and BKS strains and from The Jackson Laboratory interspecific backcross panels, (C57BL/6J x Mus spretus) F1 x C57BL/6J and (C57BL/6J x SPRET/Ei) F1 x SPRET/Ei, we constructed a consensus genetic map and narrowed Ath6 to a 1.07 +/- 0.26 cM interval between the anonymous DNA marker D12Pgn4 and the gene Nmyc1. This region is near the proximal end of murine Chromosome (Chr) 12, which is homologous to the human chromosomal region 2p24-p25. Marker order in the Ath6 region was concordant among the two crosses and The Jackson Laboratory interspecific backcross panels. This high resolution map rules out candidate genes encoding apolipoprotein B, syndecan 1, and Adam17. The two Ath6 crosses have a combined potential resolution of 0.06 cM.

Growing diversification in HMOs, 1988-1994

Based on data from annual surveys conducted by the American Association of Health Plans, this article shows growing product diversification among the nation's HMOs. Between 1988 and 1994 the percentage of HMOs offering point-of-service (POS) plans increased from roughly 20 percent to 74 percent, and the percentage offering PPO plans rose from about 25 percent to 58 percent. Today, most HMOs view themselvesas managed care organizations (MCOs) offering an array of health plans and products, not as traditional, close-ended HMOs. Future analysis of the health care industry should regard the MCO rather than the HMO as the unit of analysis. One potential developing problem is the growth of self-insured HMO plans. If current trends continue, self-insured HMO plans could erode the insurance function in the HMO market, as occurred in the indemnity market in the 1980s.