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    "textoCompleto" => "<span class="elsevierStyleSections"><p id="par0005" class="elsevierStylePara elsevierViewall">Two landmark trials conducted more than 30 years ago provided scientific evidence that&#44; under very specific circumstances&#44; long-term oxygen therapy &#40;LTOT&#41; may prolong life&#46;<a class="elsevierStyleCrossRefs" href="#bib0005"><span class="elsevierStyleSup">1&#44;2</span></a> These two trials targeted patients with chronic obstructive pulmonary disease &#40;COPD&#41; and severe daytime hypoxemia documented by direct arterial blood gas measurement&#46;</p><p id="par0010" class="elsevierStylePara elsevierViewall">Although the survival benefits of LTOT in COPD are real&#44; home oxygen is not a panacea&#46; In the British Medical Research Council&#39;s trial&#44; 500 days elapsed before any effect of LTOT on survival appeared&#44; when compared to no oxygen therapy at all&#46;<a class="elsevierStyleCrossRef" href="#bib0005"><span class="elsevierStyleSup">1</span></a> Overall&#44; at 5-year follow-up&#44; those who received oxygen had improved survival&#58; 19 of 42 &#40;42&#37;&#41; had died&#44; compared to 30 of the 45 control patients &#40;66&#37;&#41;&#46; The difference &#40;24&#37;&#41; corresponds to a number needed to treat &#40;NNT&#41; of 5&#44; which means that 5 patients must receive oxygen during 5 years in order to prevent one death over the same period&#46; Similarly&#44; the American Nocturnal Oxygen Therapy trial randomly assigned patients to receive oxygen for either 12<span class="elsevierStyleHsp" style=""></span>h a day &#40;nocturnal group&#41; or 24<span class="elsevierStyleHsp" style=""></span>h a day &#40;continuous group&#41;&#46;<a class="elsevierStyleCrossRef" href="#bib0010"><span class="elsevierStyleSup">2</span></a> The latter group actually received oxygen for an average of 19<span class="elsevierStyleHsp" style=""></span>h a day&#46; All received oxygen therapy during sleep&#46; At 24 months&#44; the overall mortality in the continuous group was 22&#46;4&#37;&#44; whereas it was 40&#46;8&#37; in the nocturnal group &#40;absolute difference&#58; 18&#46;4&#37;&#59; <span class="elsevierStyleItalic">p</span><span class="elsevierStyleHsp" style=""></span>&#61;<span class="elsevierStyleHsp" style=""></span>0&#46;01&#41;&#46; The corresponding NNT was therefore 6&#46;</p><p id="par0015" class="elsevierStylePara elsevierViewall">The good news from both trials was that &#8220;oxygen saves lives&#8221;&#46; From this moment&#44; oxygen therapy became a standard of care&#44; and confirmatory trials would be considered by many as unethical&#46; Unfortunately&#44; beyond survival&#44; the effects of LTOT on quality of life remain largely unexplored in randomized controlled trials&#46; Both the British and the American trials were conducted before the era of quality-of-life questionnaires&#46; Although suggestion from uncontrolled studies has been made that oxygen therapy improves quality of life&#44;<a class="elsevierStyleCrossRef" href="#bib0015"><span class="elsevierStyleSup">3</span></a> clinical experience rather suggests that LTOT may limit the patients&#8217; ability to remain active and may be detrimental to the rehabilitation process&#46;</p><p id="par0020" class="elsevierStylePara elsevierViewall">Thereafter&#44; oxygen therapy gained widespread acceptance by official organizations for treatment of most chronic cardio-respiratory conditions complicated by severe hypoxemia&#44; even if proof of efficacy is lacking&#46; These conditions now largely go beyond COPD and include&#44; among others&#44; cystic fibrosis&#44;<a class="elsevierStyleCrossRef" href="#bib0020"><span class="elsevierStyleSup">4</span></a> interstitial lung diseases&#44;<a class="elsevierStyleCrossRef" href="#bib0025"><span class="elsevierStyleSup">5</span></a> and pulmonary arterial hypertension&#46;<a class="elsevierStyleCrossRef" href="#bib0030"><span class="elsevierStyleSup">6</span></a> In only rare exceptions &#40;such as obesity hypoventilation<a class="elsevierStyleCrossRef" href="#bib0035"><span class="elsevierStyleSup">7</span></a> and chronic heart failure<a class="elsevierStyleCrossRef" href="#bib0040"><span class="elsevierStyleSup">8</span></a>&#41;&#44; the indication of oxygen in patients with severe hypoxemia is questioned&#46; Also&#44; new indications of oxygen therapy in COPD &#40;such as nocturnal oxygen therapy in patients with isolated nocturnal oxygen desaturation&#44; or ambulatory oxygen to correct exercise-induced desaturation&#41; have emerged&#46; To these extended indications of home oxygen&#44; one must add that&#44; even in COPD&#44; inappropriate prescriptions of home oxygen therapy are not unusual&#46;<a class="elsevierStyleCrossRef" href="#bib0045"><span class="elsevierStyleSup">9</span></a> Oxygen is everywhere&#46;</p><p id="par0025" class="elsevierStylePara elsevierViewall">Home oxygen therapy is very expensive&#46; For instance&#44; in the Canadian cohort of the Confronting COPD Survey &#40;3265 individuals&#59; mean age&#58; 63 years&#59; 44&#37; female&#41;&#44; oxygen therapy accounted for 17&#37; of the entire annual direct costs of COPD care&#46;<a class="elsevierStyleCrossRef" href="#bib0050"><span class="elsevierStyleSup">10</span></a> Also&#44; home oxygen therapy imposes sacrifices on patients and their families&#46; It is therefore surprising that it is so readily accepted by patients&#44; health care professionals and payers&#44; despite the lack of evidence to support its use in most circumstances&#46; Why is that so&#63; In addition to being safe and readily available&#44; the problem with oxygen is that its prescription always makes sense&#58; if oxygen desaturation exists&#44; its correction should help&#46;</p><p id="par0030" class="elsevierStylePara elsevierViewall">This reasoning was common before the introduction of &#8220;evidence-based medicine&#8221;&#44; when the study and understanding of basic mechanisms of disease and pathophysiologic principles were considered sufficient to guide clinical practice&#46;<a class="elsevierStyleCrossRef" href="#bib0055"><span class="elsevierStyleSup">11</span></a> A famous example proved the contrary&#46; Since ventricular arrhythmias are an important cause of death following acute myocardial infarction&#44; their suppression was expected to decrease mortality&#46; The Cardiac Arrhythmia Suppression trial &#40;CAST&#41; was stopped early after patients allocated to receive potent anti-arrhythmic drugs were found to have an increased mortality rate when compared to those receiving placebo&#46;<a class="elsevierStyleCrossRef" href="#bib0060"><span class="elsevierStyleSup">12</span></a> Similar examples&#44; although less dramatic&#44; exist in the field of oxygen therapy&#46; For instance&#44; although oxygen corrects oxygen desaturation and improves walked distance in patients with COPD and exercise-induced desaturation in laboratory testing&#44;<a class="elsevierStyleCrossRef" href="#bib0065"><span class="elsevierStyleSup">13</span></a> other trials have failed to demonstrate any long-term benefit&#46;<a class="elsevierStyleCrossRefs" href="#bib0070"><span class="elsevierStyleSup">14&#8211;17</span></a></p><p id="par0035" class="elsevierStylePara elsevierViewall">Before the introduction of &#8220;evidence-based medicine&#8221;&#44; another assumption guiding clinical practice was that unsystematic observations from clinical experience were a valid way of building and maintaining knowledge about the efficacy of treatment&#46;<a class="elsevierStyleCrossRef" href="#bib0055"><span class="elsevierStyleSup">11</span></a> Clinicians&#8217; memory is often selective&#46; The observations they recall are often anecdotal and limited to their best or worst experiences&#46; In the case of oxygen therapy&#44; bad experiences seldom occur&#46; The consequence is that prescriptions of home oxygen therapy are well anchored into clinical practice and almost never challenged&#46;</p><p id="par0040" class="elsevierStylePara elsevierViewall">Twenty years ago&#44; a shift of paradigm operated&#46; Evidence-based medicine was put forward&#46;<a class="elsevierStyleCrossRef" href="#bib0090"><span class="elsevierStyleSup">18</span></a> Evidence based medicine is the conscientious&#44; explicit&#44; and judicious use of current best evidence in making decisions about the care of individual patients&#46;<a class="elsevierStyleCrossRef" href="#bib0095"><span class="elsevierStyleSup">19</span></a> The assumptions of the new paradigm were then described as follows&#58; &#40;1&#41; the study and understanding of mechanisms of disease are necessary but insufficient guides for clinical practice&#59; &#40;2&#41; systematic observations increase the confidence clinicians can have in knowledge about efficacy of treatments&#59; &#40;3&#41; understanding certain rules of evidence is necessary to correctly interpret the medical literature&#46;<a class="elsevierStyleCrossRef" href="#bib0055"><span class="elsevierStyleSup">11</span></a></p><p id="par0045" class="elsevierStylePara elsevierViewall">This new paradigm guided us in the development and implementation of the International Nocturnal Oxygen &#40;INOX&#41; trial&#44; a multi-centre&#44; randomized&#44; placebo-controlled trial of nocturnal oxygen therapy in COPD &#40;ClinicalTrtials&#46;gov id&#58; <a href="ctgov:NCT01044628">NCT01044628</a>&#41;&#46; Prior observations suggested that nocturnal oxygen desaturation may accelerate the natural progression of COPD toward its end stages of severe hypoxemia&#44; right heart failure&#44; and death&#46;<a class="elsevierStyleCrossRefs" href="#bib0100"><span class="elsevierStyleSup">20&#44;21</span></a> Until recently&#44; it was often recommended in Canada &#40;and elsewhere around the world&#41; that nocturnal oxygen be considered if desaturation occurs for protracted periods&#46; However&#44; current evidence from two small randomized controlled trials<a class="elsevierStyleCrossRefs" href="#bib0110"><span class="elsevierStyleSup">22&#44;23</span></a> and their meta-analysis<a class="elsevierStyleCrossRef" href="#bib0120"><span class="elsevierStyleSup">24</span></a> does not support this recommendation&#46; The cost-effectiveness of nocturnal oxygen is unknown&#46; The INOX trial&#44; in which 4 clinical sites in Portugal &#40;Matosinhos&#44; Vila Nova de Gaia&#44; Coimbra and Lisboa&#41; participate&#44; is intended to address this important clinical question&#46;</p><p id="par0050" class="elsevierStylePara elsevierViewall">Of note&#44; even when data from randomized trials exist&#44; its translation into clinical practice may be problematic&#46; This is seen especially in the case of negative trials&#46; Our experience with a randomized trial of ambulatory oxygen in oxygen-dependent patients with COPD illustrates this situation&#46;<a class="elsevierStyleCrossRef" href="#bib0125"><span class="elsevierStyleSup">25</span></a> In a one-year&#44; randomized&#44; three-period&#44; crossover trial&#44; we allocated 24 patients to one of the 6 possible sequences generated by 3 interventions&#58; &#40;1&#41; standard therapy &#40;home oxygen therapy with an oxygen concentrator only&#41;&#59; &#40;2&#41; standard therapy plus as-needed ambulatory oxygen&#59; &#40;3&#41; standard therapy plus ambulatory compressed air&#46; The comparison of ambulatory oxygen vs&#46; ambulatory compressed air was double blind&#46; The main outcomes were quality of life&#44; exercise tolerance and daily duration of exposure to oxygen&#46; The trial was stopped prematurely after a planned interim analysis&#46; On average&#44; the patients used few ambulatory cylinders and ambulatory oxygen had no effect at all on any of the outcomes&#46; Our results did not support the widespread provision of ambulatory oxygen to patients with oxygen-dependent COPD&#46;</p><p id="par0055" class="elsevierStylePara elsevierViewall">The results of our trial challenged the recommendation that active patients receiving LTOT should have both stationary and mobile systems of oxygen delivery&#46;<a class="elsevierStyleCrossRefs" href="#bib0130"><span class="elsevierStyleSup">26&#44;27</span></a> The sample size of our trial was small&#46; However&#44; for both quality of life and exercise capacity&#44; the 95&#37; confidence intervals around the mean treatment effect included zero &#40;i&#46;e&#46;&#44; no effect&#41; and excluded what is usually considered as the minimal clinically important difference&#44; a clear demonstration that the negative results were not from a lack of power to detect a clinically significant difference&#46; We rather interpreted the negative results as a real indication of no benefit from ambulatory oxygen under the circumstances of the study&#46; Our results were recently confirmed by a related trial&#46;<a class="elsevierStyleCrossRef" href="#bib0140"><span class="elsevierStyleSup">28</span></a> However&#44; we are still facing clinicians&#8217; reluctance&#44; even in our own institution&#44; to limit the prescriptions of ambulatory oxygen in oxygen-dependent COPD patients&#46;</p><p id="par0060" class="elsevierStylePara elsevierViewall">Home oxygen therapy still offers a multitude of research opportunities in COPD&#46;<a class="elsevierStyleCrossRef" href="#bib0145"><span class="elsevierStyleSup">29</span></a> The INOX trial is only one of them&#46; The effects of home oxygen therapy in most cardiopulmonary conditions &#40;including interstitial lung diseases&#44; cystic fibrosis&#44; pulmonary arterial hypertension and chronic heart failure&#41; remain unexplored&#46; Randomized trials represent the most powerful method to address these important clinical questions&#46; Cost-effectiveness analyses are also needed&#46; Suggestion has been made that multicenter clinical research networks should be established to perform such clinical trials&#46;<a class="elsevierStyleCrossRef" href="#bib0150"><span class="elsevierStyleSup">30</span></a> Such efforts are challenging as they require time&#44; money and commitment from all investigators to bring the clinical trials to their ends&#46; However&#44; this investment is certainly worth it for the patients and those who will have to financially support LTOT&#46;</p><span id="sec0005" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle">Conflicts of interest</span><p id="par0065" class="elsevierStylePara elsevierViewall">The authors have no conflicts of interest to declare&#46;</p></span></span>"
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Editorial
Evidence-based oxygen therapy: Missed and future opportunities
Oxigenoterapia baseada na evidência: Oportunidades perdidas e futuras
Y. Lacasse
Corresponding author
Yves.Lacasse@med.ulaval.ca

Corresponding author.
, S. Bernard, F. Maltais
Centre de Recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec (Hôpital Laval), 2725 Chemin Ste-Foy, Québec, Québec, G1V 4G5, Canada
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    "titulo" => "Evidence-based oxygen therapy&#58; Missed and future opportunities"
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    "textoCompleto" => "<span class="elsevierStyleSections"><p id="par0005" class="elsevierStylePara elsevierViewall">Two landmark trials conducted more than 30 years ago provided scientific evidence that&#44; under very specific circumstances&#44; long-term oxygen therapy &#40;LTOT&#41; may prolong life&#46;<a class="elsevierStyleCrossRefs" href="#bib0005"><span class="elsevierStyleSup">1&#44;2</span></a> These two trials targeted patients with chronic obstructive pulmonary disease &#40;COPD&#41; and severe daytime hypoxemia documented by direct arterial blood gas measurement&#46;</p><p id="par0010" class="elsevierStylePara elsevierViewall">Although the survival benefits of LTOT in COPD are real&#44; home oxygen is not a panacea&#46; In the British Medical Research Council&#39;s trial&#44; 500 days elapsed before any effect of LTOT on survival appeared&#44; when compared to no oxygen therapy at all&#46;<a class="elsevierStyleCrossRef" href="#bib0005"><span class="elsevierStyleSup">1</span></a> Overall&#44; at 5-year follow-up&#44; those who received oxygen had improved survival&#58; 19 of 42 &#40;42&#37;&#41; had died&#44; compared to 30 of the 45 control patients &#40;66&#37;&#41;&#46; The difference &#40;24&#37;&#41; corresponds to a number needed to treat &#40;NNT&#41; of 5&#44; which means that 5 patients must receive oxygen during 5 years in order to prevent one death over the same period&#46; Similarly&#44; the American Nocturnal Oxygen Therapy trial randomly assigned patients to receive oxygen for either 12<span class="elsevierStyleHsp" style=""></span>h a day &#40;nocturnal group&#41; or 24<span class="elsevierStyleHsp" style=""></span>h a day &#40;continuous group&#41;&#46;<a class="elsevierStyleCrossRef" href="#bib0010"><span class="elsevierStyleSup">2</span></a> The latter group actually received oxygen for an average of 19<span class="elsevierStyleHsp" style=""></span>h a day&#46; All received oxygen therapy during sleep&#46; At 24 months&#44; the overall mortality in the continuous group was 22&#46;4&#37;&#44; whereas it was 40&#46;8&#37; in the nocturnal group &#40;absolute difference&#58; 18&#46;4&#37;&#59; <span class="elsevierStyleItalic">p</span><span class="elsevierStyleHsp" style=""></span>&#61;<span class="elsevierStyleHsp" style=""></span>0&#46;01&#41;&#46; The corresponding NNT was therefore 6&#46;</p><p id="par0015" class="elsevierStylePara elsevierViewall">The good news from both trials was that &#8220;oxygen saves lives&#8221;&#46; From this moment&#44; oxygen therapy became a standard of care&#44; and confirmatory trials would be considered by many as unethical&#46; Unfortunately&#44; beyond survival&#44; the effects of LTOT on quality of life remain largely unexplored in randomized controlled trials&#46; Both the British and the American trials were conducted before the era of quality-of-life questionnaires&#46; Although suggestion from uncontrolled studies has been made that oxygen therapy improves quality of life&#44;<a class="elsevierStyleCrossRef" href="#bib0015"><span class="elsevierStyleSup">3</span></a> clinical experience rather suggests that LTOT may limit the patients&#8217; ability to remain active and may be detrimental to the rehabilitation process&#46;</p><p id="par0020" class="elsevierStylePara elsevierViewall">Thereafter&#44; oxygen therapy gained widespread acceptance by official organizations for treatment of most chronic cardio-respiratory conditions complicated by severe hypoxemia&#44; even if proof of efficacy is lacking&#46; These conditions now largely go beyond COPD and include&#44; among others&#44; cystic fibrosis&#44;<a class="elsevierStyleCrossRef" href="#bib0020"><span class="elsevierStyleSup">4</span></a> interstitial lung diseases&#44;<a class="elsevierStyleCrossRef" href="#bib0025"><span class="elsevierStyleSup">5</span></a> and pulmonary arterial hypertension&#46;<a class="elsevierStyleCrossRef" href="#bib0030"><span class="elsevierStyleSup">6</span></a> In only rare exceptions &#40;such as obesity hypoventilation<a class="elsevierStyleCrossRef" href="#bib0035"><span class="elsevierStyleSup">7</span></a> and chronic heart failure<a class="elsevierStyleCrossRef" href="#bib0040"><span class="elsevierStyleSup">8</span></a>&#41;&#44; the indication of oxygen in patients with severe hypoxemia is questioned&#46; Also&#44; new indications of oxygen therapy in COPD &#40;such as nocturnal oxygen therapy in patients with isolated nocturnal oxygen desaturation&#44; or ambulatory oxygen to correct exercise-induced desaturation&#41; have emerged&#46; To these extended indications of home oxygen&#44; one must add that&#44; even in COPD&#44; inappropriate prescriptions of home oxygen therapy are not unusual&#46;<a class="elsevierStyleCrossRef" href="#bib0045"><span class="elsevierStyleSup">9</span></a> Oxygen is everywhere&#46;</p><p id="par0025" class="elsevierStylePara elsevierViewall">Home oxygen therapy is very expensive&#46; For instance&#44; in the Canadian cohort of the Confronting COPD Survey &#40;3265 individuals&#59; mean age&#58; 63 years&#59; 44&#37; female&#41;&#44; oxygen therapy accounted for 17&#37; of the entire annual direct costs of COPD care&#46;<a class="elsevierStyleCrossRef" href="#bib0050"><span class="elsevierStyleSup">10</span></a> Also&#44; home oxygen therapy imposes sacrifices on patients and their families&#46; It is therefore surprising that it is so readily accepted by patients&#44; health care professionals and payers&#44; despite the lack of evidence to support its use in most circumstances&#46; Why is that so&#63; In addition to being safe and readily available&#44; the problem with oxygen is that its prescription always makes sense&#58; if oxygen desaturation exists&#44; its correction should help&#46;</p><p id="par0030" class="elsevierStylePara elsevierViewall">This reasoning was common before the introduction of &#8220;evidence-based medicine&#8221;&#44; when the study and understanding of basic mechanisms of disease and pathophysiologic principles were considered sufficient to guide clinical practice&#46;<a class="elsevierStyleCrossRef" href="#bib0055"><span class="elsevierStyleSup">11</span></a> A famous example proved the contrary&#46; Since ventricular arrhythmias are an important cause of death following acute myocardial infarction&#44; their suppression was expected to decrease mortality&#46; The Cardiac Arrhythmia Suppression trial &#40;CAST&#41; was stopped early after patients allocated to receive potent anti-arrhythmic drugs were found to have an increased mortality rate when compared to those receiving placebo&#46;<a class="elsevierStyleCrossRef" href="#bib0060"><span class="elsevierStyleSup">12</span></a> Similar examples&#44; although less dramatic&#44; exist in the field of oxygen therapy&#46; For instance&#44; although oxygen corrects oxygen desaturation and improves walked distance in patients with COPD and exercise-induced desaturation in laboratory testing&#44;<a class="elsevierStyleCrossRef" href="#bib0065"><span class="elsevierStyleSup">13</span></a> other trials have failed to demonstrate any long-term benefit&#46;<a class="elsevierStyleCrossRefs" href="#bib0070"><span class="elsevierStyleSup">14&#8211;17</span></a></p><p id="par0035" class="elsevierStylePara elsevierViewall">Before the introduction of &#8220;evidence-based medicine&#8221;&#44; another assumption guiding clinical practice was that unsystematic observations from clinical experience were a valid way of building and maintaining knowledge about the efficacy of treatment&#46;<a class="elsevierStyleCrossRef" href="#bib0055"><span class="elsevierStyleSup">11</span></a> Clinicians&#8217; memory is often selective&#46; The observations they recall are often anecdotal and limited to their best or worst experiences&#46; In the case of oxygen therapy&#44; bad experiences seldom occur&#46; The consequence is that prescriptions of home oxygen therapy are well anchored into clinical practice and almost never challenged&#46;</p><p id="par0040" class="elsevierStylePara elsevierViewall">Twenty years ago&#44; a shift of paradigm operated&#46; Evidence-based medicine was put forward&#46;<a class="elsevierStyleCrossRef" href="#bib0090"><span class="elsevierStyleSup">18</span></a> Evidence based medicine is the conscientious&#44; explicit&#44; and judicious use of current best evidence in making decisions about the care of individual patients&#46;<a class="elsevierStyleCrossRef" href="#bib0095"><span class="elsevierStyleSup">19</span></a> The assumptions of the new paradigm were then described as follows&#58; &#40;1&#41; the study and understanding of mechanisms of disease are necessary but insufficient guides for clinical practice&#59; &#40;2&#41; systematic observations increase the confidence clinicians can have in knowledge about efficacy of treatments&#59; &#40;3&#41; understanding certain rules of evidence is necessary to correctly interpret the medical literature&#46;<a class="elsevierStyleCrossRef" href="#bib0055"><span class="elsevierStyleSup">11</span></a></p><p id="par0045" class="elsevierStylePara elsevierViewall">This new paradigm guided us in the development and implementation of the International Nocturnal Oxygen &#40;INOX&#41; trial&#44; a multi-centre&#44; randomized&#44; placebo-controlled trial of nocturnal oxygen therapy in COPD &#40;ClinicalTrtials&#46;gov id&#58; <a href="ctgov:NCT01044628">NCT01044628</a>&#41;&#46; Prior observations suggested that nocturnal oxygen desaturation may accelerate the natural progression of COPD toward its end stages of severe hypoxemia&#44; right heart failure&#44; and death&#46;<a class="elsevierStyleCrossRefs" href="#bib0100"><span class="elsevierStyleSup">20&#44;21</span></a> Until recently&#44; it was often recommended in Canada &#40;and elsewhere around the world&#41; that nocturnal oxygen be considered if desaturation occurs for protracted periods&#46; However&#44; current evidence from two small randomized controlled trials<a class="elsevierStyleCrossRefs" href="#bib0110"><span class="elsevierStyleSup">22&#44;23</span></a> and their meta-analysis<a class="elsevierStyleCrossRef" href="#bib0120"><span class="elsevierStyleSup">24</span></a> does not support this recommendation&#46; The cost-effectiveness of nocturnal oxygen is unknown&#46; The INOX trial&#44; in which 4 clinical sites in Portugal &#40;Matosinhos&#44; Vila Nova de Gaia&#44; Coimbra and Lisboa&#41; participate&#44; is intended to address this important clinical question&#46;</p><p id="par0050" class="elsevierStylePara elsevierViewall">Of note&#44; even when data from randomized trials exist&#44; its translation into clinical practice may be problematic&#46; This is seen especially in the case of negative trials&#46; Our experience with a randomized trial of ambulatory oxygen in oxygen-dependent patients with COPD illustrates this situation&#46;<a class="elsevierStyleCrossRef" href="#bib0125"><span class="elsevierStyleSup">25</span></a> In a one-year&#44; randomized&#44; three-period&#44; crossover trial&#44; we allocated 24 patients to one of the 6 possible sequences generated by 3 interventions&#58; &#40;1&#41; standard therapy &#40;home oxygen therapy with an oxygen concentrator only&#41;&#59; &#40;2&#41; standard therapy plus as-needed ambulatory oxygen&#59; &#40;3&#41; standard therapy plus ambulatory compressed air&#46; The comparison of ambulatory oxygen vs&#46; ambulatory compressed air was double blind&#46; The main outcomes were quality of life&#44; exercise tolerance and daily duration of exposure to oxygen&#46; The trial was stopped prematurely after a planned interim analysis&#46; On average&#44; the patients used few ambulatory cylinders and ambulatory oxygen had no effect at all on any of the outcomes&#46; Our results did not support the widespread provision of ambulatory oxygen to patients with oxygen-dependent COPD&#46;</p><p id="par0055" class="elsevierStylePara elsevierViewall">The results of our trial challenged the recommendation that active patients receiving LTOT should have both stationary and mobile systems of oxygen delivery&#46;<a class="elsevierStyleCrossRefs" href="#bib0130"><span class="elsevierStyleSup">26&#44;27</span></a> The sample size of our trial was small&#46; However&#44; for both quality of life and exercise capacity&#44; the 95&#37; confidence intervals around the mean treatment effect included zero &#40;i&#46;e&#46;&#44; no effect&#41; and excluded what is usually considered as the minimal clinically important difference&#44; a clear demonstration that the negative results were not from a lack of power to detect a clinically significant difference&#46; We rather interpreted the negative results as a real indication of no benefit from ambulatory oxygen under the circumstances of the study&#46; Our results were recently confirmed by a related trial&#46;<a class="elsevierStyleCrossRef" href="#bib0140"><span class="elsevierStyleSup">28</span></a> However&#44; we are still facing clinicians&#8217; reluctance&#44; even in our own institution&#44; to limit the prescriptions of ambulatory oxygen in oxygen-dependent COPD patients&#46;</p><p id="par0060" class="elsevierStylePara elsevierViewall">Home oxygen therapy still offers a multitude of research opportunities in COPD&#46;<a class="elsevierStyleCrossRef" href="#bib0145"><span class="elsevierStyleSup">29</span></a> The INOX trial is only one of them&#46; The effects of home oxygen therapy in most cardiopulmonary conditions &#40;including interstitial lung diseases&#44; cystic fibrosis&#44; pulmonary arterial hypertension and chronic heart failure&#41; remain unexplored&#46; Randomized trials represent the most powerful method to address these important clinical questions&#46; Cost-effectiveness analyses are also needed&#46; Suggestion has been made that multicenter clinical research networks should be established to perform such clinical trials&#46;<a class="elsevierStyleCrossRef" href="#bib0150"><span class="elsevierStyleSup">30</span></a> Such efforts are challenging as they require time&#44; money and commitment from all investigators to bring the clinical trials to their ends&#46; However&#44; this investment is certainly worth it for the patients and those who will have to financially support LTOT&#46;</p><span id="sec0005" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle">Conflicts of interest</span><p id="par0065" class="elsevierStylePara elsevierViewall">The authors have no conflicts of interest to declare&#46;</p></span></span>"
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Article information
ISSN: 08732159
Original language: English
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