Characteristics of long-term home oxygen therapy users in the municipality of Curitiba , Brazil

Introduction: Long-term home oxygen therapy (LTOT) can be successfully used in the treatment and prevention of chronic lung diseases, as it improves quality of life, increases survival, and reduces the lenght of hospital stays. However, to the authors’ knowledge there are no descriptive studies with details of the * DK: Doctoral student, email: demetriakovelis@gmail.com PLC: BS, email: paola.luma@gmail.com LIS: BS, email: ligiainezsilva@hotmail.com JRS: MS, email: sierra.juanricardo@gmail.com PRMS: PhD., email: wsandoval@pucpr.br SV: PhD., email: svalderramas@uol.com.br

Introduction: Long-term home oxygen therapy (LTOT) can be successfully used in the treatment and prevention of chronic lung diseases, as it improves quality of life, increases survival, and reduces the lenght of hospital stays.However, to the authors' knowledge there are no descriptive studies with details of the

Introduction
The use of Long-Term Oxygen Therapy (LTOT) in the treatment and prevention of chronic lung diseases is already well consolidated in the literature, as well as the control of cor pulmonale episodes, decreased polycythemia [1], and the increased tolerance to exercises, with a direct impact on the quality of life and chances of survival [1 -3].
Another benefit reached is the reduced length of hospital stay and number of hospitalizations, thus decreasing costs for maintaining the treatment, with a consequent decrease in expenses by the Brazilian National Health System (Sistema Único de Saúde [SUS]).Furthermore, it allows for maintaining the patient in their residence together with their family, providing them more comfort [4].
The LTOT is generally prescribed for clinically stable patients with optimized medical therapy, showing PaO 2 < 55 mmHg or SaO 2 < 88% in environmental air; and for borderline patients concerning PaO 2 , who present at least one of the following conditions: polyglobulia, pulmonary hypotension, or falls in oxygen concentration during exercise [2,5].Thus, oxygen therapy fits into the context of resolving and preventing manifestations of tissue hypoxemia during everyday activities [6][7][8][9][10][11].
The LTOT program was created by SUS, benefiting patients with chronic hypoxemia who have not been indicated for hospitalization.According to information provided by the Municipal Health Secretariat (SMS), the LTOT program was implemented in 2011 in the State of Paraná, Brazil, and can currently be found in all regions of the state, attending about one thousand beneficiaries.The city of Curitiba is responsible for the loaning out and treatment maintenance for home oxygen therapy and provides a kit consisting of a cylinder, concentrator, extension and nasal catheter (SMS -2015).The literature has reported on some questions such as the social and clinical repercussions of LTOT in various countries [6,[12][13][14], as well as in some Brazilian cities [15][16][17][18].However, the authors are unaware of descriptive studies reporting the clinical and social profiles of patients who use LTOT in the State of Paraná.They believe that descriptive studies concerning the profile of this population could contribute by providing information that would give a wider vision of their reality and offer subsidies for improved care planning, such as new evaluation and treatment strategies for these patients.
Thus, the objectives of this study were: 1) analyzing the clinical and socio-demographic profiles of patients attended by the LTOT program in the municipality of Curitiba; 2) identifying the number of comorbidities and the main symptoms and discomforts related to the use of LTOT.

Methods
This was a descriptive, observational study, carried out in the municipality of Curitiba/Paraná/ Brazil from May to July 2015, after project approval by the Ethics Committee (No. 481.008/2013).
Regardless of age, gender, and disease, the inclusion criterion was that the individual should be registered in the Long-term Home Oxygen Therapy Program of the Municipal Health System (SMS) of Curitiba for the period mentioned and agree to participate in the study.
Patient profile characterization was carried out by a duly trained physical therapist, in a single telephone interview, using a form elaborated by the researchers, which included categorized information concerning: age, gender, education level, marital status, family income, main diagnosis, number of comorbidities, smoking history, if he/she carries out any physical activity, hospitalization in the last year due to disease exacerbation, main symptoms, amount of oxygen and hours of use per day, catheter length and discomfort when using oxygen.The Charlson Comorbidities Index (CCI) was also calculated, as it is described as an important mortality indicator.Such index calculates the risk of patient morbidity, considering associated comorbidities, through a specific scoring system for each clinical condition, with weights varying from zero to six [19].
Information collected in the interviews was grouped into three dimensions, according to the structure proposed by WHO to describe the characteristics of chronic patients, including: 1) clinical characteristics of the LTOT users; 2) sociodemographic aspects and system-related factors; and 3) patients' monthly income.
Data analysis was carried out using the Windows SPSS statistical program software, version 22.0.The descriptive analysis of data was represented by the absolute and relative frequency, mean and standard deviation, median, and 25-75% percentiles.

Results
Of the 506 LTOT users in the period from May to June 2015, 120 (23%) did not carry out the interview, whereas some did not agree to participate in the study (n = 19), died (n = 18), were former users (n = 8) or hospitalized (n = 5), and some were not found (n = 70), totaling 386 users, as shown in Figure 1.The most prevalent disease was chronic obstructive pulmonary disease (COPD) (58.5% of the population evaluated), followed by pulmonary fibrosis (7.5%) and asthma (7.2%), as shown in Figure 2. Tables 1 and 2 give detailed descriptions of the clinical and socio-demographic characteristics, respectively.Regarding socio-demographic characteristics, most of the users were female, married or widowed, and educated up to complete primary education (Table 2).The number of rooms in the patients' homes were from 4 to 6 in 54.9% of the cases, and the length of the O 2 extension was on average 7.23 ± 2.37 meters, such that the number of rooms reached by the O 2 catheter was from 2 to 3 for 42.3% of the interviewees.Regarding income, 78.5% of the users earned from 1 to 3 minimum wages (Table 3).

Discussion
The results of this study provided a picture of the LTOT users' characteristics in the city of Curitiba/ Parana/Brazil, generating potentially valuable information about their health state and social factors.
From this study, one can see that most LTOT users had been diagnosed with COPD.The presence of this disease can justify some of the characteristics shown by this study, such as an average age of 67 (± 20.4) and a high prevalence of ex-smokers who were physically inactive.In addition, since this is a disease more frequently found in older adults [15,22,23] and considering the increased life expectancy of Brazilian women in comparison with Brazilian men [24,25], this justifies the fact that more than 60% of those interviewed were of the female gender and that a greater number of the LTOT users were older.
Although COPD was a disease traditionally more common in men, in recent years the COPD prevalence and mortality increased more rapidly in women than in men, apparently due to a change in smoking habits among women [26].In addition, studies have shown that women with no history of smoking are 1.5 times more likely to be diagnosed with COPD than men [27,28].Pinkerton K.E.et al. stated that basic differences in anatomy and physiology between men and women undoubtedly influence both the course of respiratory infections caused by the disease as the response to treatment [29].
Of the individuals interviewed, 84.5% said they did not undertake any type of physical activity, corroborating the results shown in another study, in 2014, in the municipality of Botucatu, SP, Brazil, where a research group found a high prevalence of physical inactivity amongst the participants (98.1%) [30].
Regarding the use of O 2 , most individuals interviewed in this study (55.7%) used an average of 2.6 l/min in a continuous way, similar to research carried out previously [6,16,18,30].However, other studies have shown the use of supplementary oxygen for shorter periods of time, such as 18 hours [13,16], 9.8 hours [29], and 8 to 10 hours [18].Such scenario dshows the lack of standardization in the LTOT prescription, possibly due to the fact that many patients had not received a precise diagnosis or stratification of their clinical decompensation, making the oxygen use empirical since some of them used it continuously and others intermittently, with no pre-established criterion or specific orientation by the person who prescribed it.
The main symptom reported by the interviewees was dyspnea (81.3%), corroborating the results of a survey carried out in the city of São Paulo, Brazil, in which 66.6% of LTOT users reported the same symptom [30].Even higher levels of dyspnea (91%) were described in a study carried out in Japan [6].The authors emphasize the fact that, although the literature describes the use of supplementary oxygen as being inversely proportional to the presence of the dyspnea sensation [6,31], it appears this is not observed in clinical practice.
The main LTOT treatment-related discomforts reported by the patients were dry nostrils (33%) and immobility (13%), but 40% reported no discomfort during treatment.In another survey carried out in Goiânia, Brazil, the authors found lower percentages of discomfort, with 8.1% reporting dry nostrils and 6.3% immobility [16], a difference that could be explained by the climate disparity between the two cities.
Regarding the number of hospitalizations due to exacerbation of the clinical condition, 53.4% of the participants reported at least one hospitalization per year and, of these, 27.9% required 3-month hospitalization prior to the research.
As to the presence of comorbidities, this study found a lower value for the Charlson Comorbidity Index (CCI) [19][20][21] than that reported by Santos et al.
(2.36 versus 5.2) [30].Marti et al. [32] demonstrated that the risk of death for respiratory causes among patients with COPD was three to five times higher for a CCI ≥ 2 and concluded that, for those COPD patients using long-term home oxygen therapy, nonrespiratory variables such as the body mass index (BMI) < 25 kg/m 2 and comorbidities were factors leading to a prognosis of mortality due to respiratory causes or otherwise.
Since the information shows a close relationship between BMI and mortality in these patients, the fact this information was not obtained in this research must be considered as a limitation of the study.Furthermore, other limitations are the lack of information concerning the medical follow-up time for the use of LTOT, adherence to the time of use, and used/prescribed O 2 flow.
On average, the length of the extension used by the patients was 7 meters, contrary to that reported by other studies (2 meters) [16,30].The authors believe that an evaluation of the O 2 extension is very relevant since it represents an important determinant of patient locomotion within their residence.Although the number of rooms reported in the residences was from 4 to 6, the number of rooms reached by the O 2 catheter would be from 2 to 3.
With respect to marital status, the sample used in this study consisted mostly of married and/or widowed individuals, in agreement with other national studies [15,30].The importance of investigating marital status was due to the fact there is an association between social support and greater levels of physical activity and involvement with pulmonary rehabilitation in adults with COPD [33].
Individuals' education level is also a relevant data for discussion since it is directly related to their self-care capacity and quality of life, with direct repercussions on the evolution of chronic diseases [15,34,35].Thus, as in many other studies [15,18], the education level most commonly observed was incomplete primary education (33.9%), suggesting that both self-care and quality of life could be harmed among these individuals.
The sample included 47.9% of individuals with incomes from 2 to 3 minimum salaries, a mean slightly higher than that found in other states such as São Paulo [15,30] and Fortaleza [17].Income is also considered to be a determinant factor in the treatment of chronic patients, considering that low incomes are associated with more frequent exacerbations and increased COPD risks [36].According to Kawachi & Kennedy (1999), income can be used as a powerful predictor of mortality; the lower the income, the greater the risk of death and the worse the selfreported quality of health [37].
One of the limitations of this study was the lack of a clinical and functional evaluation.The limited resources for locomotion to the patients' residences and the fact that most of them encountered difficulty in going to the locations to carry out the tests due to the heavy equipment, as well as the high cost of recharging the oxygen cylinders, made an inperson evaluation impossible.Nevertheless, this study provided initial information on which future research could be based, aimed at confirming and/ or establishing clinical and functional diagnoses for these individuals, so that they can receive pulmonary rehabilitation according to their needs.
Knowing the profiles of LTOT patients is of paramount importance for providing subsidies to professionals of the Home Health Care Program, aimed at elaborating a plan for interdisciplinary action with preventative and curative strategies, favoring adhesion to the proposed services and strategies and, consequently, an improvement in the population health [38].

Conclusion
Patients of the LTOT program in the municipality of Curitiba were mainly elderly women with COPD, who used O 2 continuously, frequently reporting dyspnea, presenting low family income and education levels.This study provided evidence on the importance of health professionals taking educational and preventative measures aimed at this population, to minimize the impact of COPD in the community and to provide information for planning necessary measures, leading to benefits and an improvement of domiciliary health care.

Figure 2 -
Figure 2 -Distribution of users according to their clinical diagnoses.
± Standard deviation; Median and [inter-quartile range].*intermittent = discontinuous use of LTOT, use for short periods (1 to 2 hours), when feeling out of breath.

Table 1 -
Clinical characteristics of the LTOT users Discomfort in using LTOT n (%)

Table 2 -
Distribution of the LTOT users according to sociodemographic characteristics

Table 3 -
Incomes and costs of the population using LTOT in Curitiba