Perceived Satisfaction With Long-Term Oxygen Delivery Devices Affects Perceived Mobility and Quality of Life of Oxygen-Dependent Individuals With COPD

Discussion

Our study findings indicate that perceived satisfaction with an LTOT device affects perceived mobility in oxygen-dependent individuals with COPD. Additionally, we found that both perceived satisfaction with an LTOT device and perceived mobility affect perceived QOL in these individuals. Although various aspects of long-term oxygen therapy have been studied extensively, very few studies have focused on the impact of oxygen delivery devices on mobility and QOL. Moreover, the few studies that address this issue have been conducted in Europe and may not be reflective of the COPD population in the United States. The scarcity of research in this area may be attributed to the reality that Medicare reimbursement for LTOT is modality-neutral,²² which means that physicians are required to prescribe an oxygen flow but not the LTOT device. Additionally, it has been noted that LTOT is usually prescribed before the patient is discharged from the hospital by acute care physicians who may not have the requisite knowledge about LTOT devices to specify the most appropriate device for the patient in the prescription. Consequently, the selection of LTOT devices has been mostly left up to the suppliers of durable medical equipment.²²

In this study of oxygen-dependent individuals with COPD, liquid oxygen system use significantly and positively affected mobility and QOL, whereas cylinder use significantly and negatively affected mobility and perceived QOL. Because mobility is a key determinant of satisfaction, it is understandable why oxygen devices that are perceived to increase mobility would result in a higher perceived QOL. COPD outcomes largely depend on adherence to the prescribed treatment regimen (including quitting smoking, if applicable), remaining physically active, and improving mental health.^7,8 Some of the psychological hallmarks of COPD are feelings of isolation, depression, and anxiety.²³ Many of these feelings may be directly related to lack of mobility due to the prescribed oxygen delivery device. If the device is too heavy, too conspicuous, too cumbersome, or too limiting and/or makes the user feel self-conscious, the patient may become withdrawn and less physically active. This in turn increases the likelihood of poor COPD symptom control and increased emergency room visits and hospitalizations. A meta-analysis of COPD health-care behavior self-management interventions²⁴ found that physical activity improved HRQOL. The researchers postulated that physical activity contributes to less dyspnea and fatigue, with concomitant improvement in mental health and social engagement, resulting in improved HRQOL.

Based on comments from survey participants, size E cylinders are considered heavy, conspicuous, cumbersome, and limiting for many of these individuals. The following quotes from 4 of the survey participants highlight their perceived limitations to mobility imposed by portable LTOT devices: Absolutely hate the E tanks that represent my portable unit. They are heavy, ugly and run out of O₂ within 2 ½ h. My normal setting is 5 for activity. In the past, I was using a POC and then had to convert to D tanks using [a] home fill system to fill extra tanks for all trips away from home. I always encouraged COPD patients to stay active. Now, I find that I am the one that has slowed down almost to a stop.I would be more mobile and better able to be independent if I had a more efficient portable O₂ system. The tanks are heavy and take extra oxygen to even carry them. I've always maintained that if you can carry those heavy tanks you don't need O₂.The previous cylinders hinders us due to the weight. If you can't breathe, adding additional weight and [a] cumbersome device hinders a person's life that is already hindered.The tank and shoulder bag I carry weigh 5 pounds. For some people that is not a lot, but I am a small woman who has lost a lot of strength over my years with COPD. It is bulky and hard to manage while cleaning house, working in the yard, taking care of a pet or children, etc.

It is clear from the results of this survey that this type of LTOT device may negatively affect the mobility and perceived QOL for oxygen-dependent persons with COPD. It must be noted that our survey sample consisted primarily of individuals who reported that they have severe (80%) and moderate COPD (17%).

Our survey results corroborate the findings of a previous Swedish study, which found that a liquid oxygen system as compared with a concentrator enhanced QOL in subjects with chronic hypoxemia as measured by the Sickness Impact Profile and the EuroQol instruments.²⁵ The results of this study and our survey are not consistent with the findings of a study by Casaburi et al,²⁶ in which COPD subjects with severe hypoxemia were randomized to use either E oxygen cylinders or lightweight cylinders (M-6 cylinders) weighing only 3.6 pounds. The researchers found that ambulatory oxygen use declined from baseline in COPD subjects who were given the lightweight oxygen cylinders. At the end of the study, there was no significant difference in the use of ambulatory oxygen between the 2 groups of subjects, indicating that lightweight LTOT devices did not improve mobility in those subjects.²⁶ A significant limitation of the study by Casaburi et al²⁶ is that it was underpowered; the authors noted that the sample size needed to detect an increase in daily oxygen use of 3 h in the lightweight LTOT device group was 100 participants, but only 17 participants completed the study. Additionally, the lightweight oxygen cylinder (M-6) that was used may not have been optimal for ambulation in this patient population due to fear of oxygen depletion. The authors stated that the lightweight device was set to deliver a pulse dose between 2 and 5 L/min, but this may not have been sufficient for these subjects during ambulation. Indeed, several studies have found that whereas oxygen-conserving devices meet the oxygen needs of subjects at rest, they may fail to do so during periods of activity due to various patient- and device-related factors.^27–29

The results of our survey also conflict with the findings of a recent multi-center parallel group, randomized clinical trial³⁰ of LTOT versus no LTOT in 738 subjects with COPD and moderate resting or exercise-induced desaturation. The results of this clinical trial indicate that ambulatory oxygen does not improve the QOL, as measured with the Quality of Well-Being scale in subjects with moderate or exercise-induced desaturation.³⁰ However, this study had several significant limitations, including the use of different LTOT devices across participants in the various study centers. Moreover, the portable oxygen device used for ambulation was not specified. Additionally, 75% of the participants were male, which is not representative of the COPD population in the United States, where the COPD rate among women is higher than in men.¹ The authors also reported significant bias in self-reported adherence to prescribed LTOT; consequently, the results of this clinical trial demonstrating no mortality benefit of LTOT should be interpreted with caution, given the complexity of COPD and the multiple factors that influence which individuals may benefit from oxygen supplementation.

Participant recruitment for our survey was achieved via an Internet-based method and is consistent with the growing trend among researchers of tapping into a more diverse population from the Internet.³¹ There is mounting evidence that results from research in which participants are recruited using Internet-based methods are as valid and reliable as results from research in which traditional means of participant recruitment are used. Casler et al³¹ compared results of a behavioral study from 3 different groups of participants who were recruited using the traditional method of recruiting undergraduate psychology students and using 2 Internet-based methods, namely crowd-sourcing and social media. The 3 different groups of participants were asked to complete a behavioral task, which was adapted to fit an online context for the online participants. The participants who were traditional undergraduate recruits completed the task one-on-one with an experimenter in a university lab test room,³¹ whereas the online participants were allowed to complete the task at their leisure. The study findings demonstrated that there was no difference between the 3 groups with regard to the expected behavioral outcome. It was also noted that the online participants were more diverse than the participants recruited via the traditional method and were more representative of the general population. The researchers concluded that participants recruited online can provide valid data. Health care-related studies, including clinical trials, are also increasingly relying on online recruitment to obtain more diverse participants, decrease recruitment costs, and increase the number of participants who enroll in a study, especially for studies of rare diseases and risky health behaviors in which participant recruitment by traditional methods is challenging.^32–34

Since our study relied on self-reported data, the validity of results may be compromised due to limitations inherent in this study design, such as recall bias, respondents' ability to understand the survey questions, response bias, and differences in how respondents interpret the rating scales used in the survey. The variances in mobility and device satisfaction can also be attributed to differences in personal perceptions of satisfaction among individual survey participants. Although the survey asked participants to rank levels of satisfaction with their oxygen device, QOL, and mobility, it is difficult to truly assess personal preferences. Moreover, the degree of mobility that is considered acceptable to one individual may be perceived as severely limiting to another. Additionally, because study subjects were not selected at random, there may very well be selection bias in that the portable device that was in use at the time of the study may have been influenced by the subject's mobility at baseline. Finally, because 80% of study subjects were female with severe COPD and the ability to use the Internet, the study cannot be generalized to the entire COPD population.