Sleep-related breathing disorders cause partial or complete obstruction of one’s respiratory system during sleep, resulting in many complications such as low blood oxygen, high blood pressure, even heart attack or stroke. The severity of the symptoms varies between the different types of breathing disorders, including obstructive sleep apnea, central and mixed sleep apnea, sleep-related hypoventilation and more. The most common one, the obstructive sleep apnea (OSA) affects about 20% of men and 9% of women in the US alone, which is a big increase comparing to the estimated 3% of the population in the 90s. This is believed to be due to a number of factors, including higher obesity and asthma rates, pollution, but also due to a more precise diagnostic system – polysomnography was discovered and readjusted at the end of the 20th century to monitor respiratory airflow and some other breathing-related functions in our bodies during sleep. To date, it remains the one sure way to diagnose this sleep disorder, also measuring one’s heart rhythm, brain activity, eye movements and so forth.
Several options exist for treating OSA, the most widespread and efficient one involving a CPAP machine. This choice has been proven time and time again as the most effective and remains a go-to option in most circumstances unless it isn’t adhered to for a period long enough to work. Many people find CPAP uncomfortable and stop using it as soon as their OSA starts to feel better. As a result, the disorder symptoms return in full swing, and a recent study highlights this as the main reason for hospital readmissions among OSA patients. Before we get into the study, we will review OSA and CPAP treatments for some context and clarification first.
Obstructive Sleep Apnea (OSA)
OSA is frequently accompanied by loud snoring, interrupted by periods when the airflow is reduced or blocked. This is followed by choking or gasping for air which usually wakes up the person, but only for a brief moment before they resume sleep. Depending on how often this happens, OSA can be:
- Mild – the episode happens 5-14 times every hour
- Moderate – the incident occurs 15-30 times every hour
- Severe – the event occurs over 30 times every hour
Everybody is at a lower or higher risk of developing OSA, depending on some contributing factors such as:
- Weight. High blood pressure, heart disease, and diabetes are all linked to obesity and known to increase your chance for developing OSA as well.
- Neck size – over 17 inches for men, and over 16 inches for women increase the risk of OSA.
- Age. The older you are, the more chances you have at developing OSA, at least until you hit 60. Statistically, the incidence rate drops after that age.
- Sex. Men are at least two times more likely to develop OSA than women, possibly due to their higher obesity rates and larger neck dimensions.
- Allergies and asthma both increase the risk because of more sensitive airways, increased mucus production and congestion.
- Family history. The exact predisposing genetic factor isn’t known yet, but its existence is evident, given that you are more likely to experience OSA if you have a relative who suffers it, too.
- Retrognathia, meaning that your lower jaw is smaller than the upper one.
- Narrow airways. These sometimes naturally “happen,” perhaps due to a larger than average tongue or enlarged tonsils.
Treatments usually consist of some lifestyle changes and some specialty therapy with machines like CPAP (more about that in a bit).
Lifestyle changes include:
- Weight loss – beneficial for everybody whose BMI is outside of the optimal.
- Switching sleeping positions from back to the side, preferably left, as this aligns the organs and the spine properly while reducing snoring and airway obstruction.
- Avoiding opioids such as alcohol, pills, cigarettes, etc.
- Managing secondary conditions if they are present – asthma or allergies, GI issues or another medical condition.
- Nasal sprays if congestion is what disrupts the breathing.
Continuous positive air pressure (CPAP) is a type of PAP treatment most suitable for OSA and some other breathing conditions. It is a machine that is put next to a patient’s bed, connected to a mask they’re supposed to put on at bedtime via a hose. The treatment lasts the entire night. The machine humidifies the air and provides it with high pressure directly into the mask, hence the name. This enables the patient’s airways to remain open, or reduces their obstruction and improves their sleep quality. The duration of this treatment and the specific settings on the CPAP machine depend on the doctor’s prescription based on the severity of your OSA and your overall health. For example, if you have OSA but also some gastrointestinal issue that causes acid reflux, CPAP therapy is not the best option – the air will sometimes stray and pass through the esophagus which is already weak enough, thus exacerbating acid reflux.
Nonadherence to CPAP associated with increased 30-day hospital readmissions
Specialists sought out to discover the effect of nonadherence to CPAP on hospital readmissions expecting to get the general overview of the situation so they conducted this study including 345 patients at the VA Long Beach Medical Center that satisfied the criteria (they were diagnosed with OSA, hospitalized at some point or another from January 2007 to December 2015 and prescribed CPAP therapy). Out of that number, 183 people adhered to their CPAP therapy while 162 didn’t. The purpose of the study was to establish the effect of nonadherence in terms of all-cause, cardiovascular-cause and pulmonary-cause hospital readmissions within thirty days after the initial, index admission discharge from the hospital. Excluded were patients without records of adherence to CPAP therapy and polysomnography to confirm OSA, those who passed away in the hospital during index admission and those transferred to another facility within the same day of index admission.
All-cause readmissions include cardiovascular and pulmonary-cause, as well as other cause readmissions such as renal, urologic, gastrointestinal, neurologic, psychiatric, infection, etc.
Cardiovascular-cause readmissions refer to those of congestive heart failure, coronary syndrome, arrhythmia, peripheral cardiovascular disease, and some others.
Pulmonary-cause readmissions were due to pulmonary hypertension, asthma, hypoxia, obesity hypoventilation, pulmonary embolism, and interstitial lung disease.
The average age of the patients from the adherent group was 66.3 years, and 62.3 in the nonadherent group. This, along with the patients’ sex, BMI, race, environment, and home conditions, the overall state of health and medical history was taken into account before measuring the results. Although the CPAP adherent group was older on average, the expected increase, especially in cardiovascular-cause of readmission, wasn’t apparent. The incidence rate both for all-cause and cardiovascular-cause readmissions was significantly higher in the nonadherent group, and their stay in the hospital was slightly longer, too.
The study confirmed an existing hypothesis that not sticking with your CPAP treatment plan is more likely to get you back into the hospital.
The cardiovascular causes were due to atrial fibrillation (29.0%), myocardial ischemia (22.5%), and congestive heart failure (19.3%), and to no surprise, because these are often the result of frequent apnea episodes and hypoxemia, both of which are neutralized with CPAP therapy.
The pulmonary-related readmissions were also higher among the nonadherent group, but not as much as initially expected, and not of significance to this study.
All-cause readmission unrelated to the two causes mentioned was mostly urologic (10.7%), infection (8.0%), and psychiatric (5.3%). Specialists are just starting to take a closer look into these factors and their association with OSA and sleep in general.
Limitations and critique
Although its significance is notable if only as a single study, this work has faced a couple of flaws from the start and they are worth mentioning for clarification and readjustments for future studies.
For starters, it was conducted in a Veterans Affairs Medical Center, which is a specific target group and not as general as one would hope for a study of this sort. People from this subject group were predominantly white, male, have a lower income, have a history of substance abuse or have a second existing chronic condition. Cause-consequence effect wasn’t completely transparent either, as with most studies. One can’t be sure that CPAP nonadherence was the reason for a future event, only that the event was more likely to happen to people from the nonadherent group, although researchers did include many other contributing factors.
Further, most of the patients who didn’t make the criteria for this study were excluded because of the lack of sleep clinic follow-up within a year after the first hospitalization. That excludes their results as well, whether they continued the prescribed CPAP therapy or not.
Lastly, because of its small dimensions, the study might have missed some patterns, while some of the patterns noticed could have proved irrelevant on a larger subject group. For this reason, the study remains more a stepping stone for future research, than a sole authoritative source of information.