Chronic obstructive pulmonary disease (COPD) is a complex chronic, progressive respiratory illness, with high morbidity and mortality and high public healthcare costs.1 One of the characteristic aspects of this disease is the presence of acute exacerbations that lead to deterioration in the quality of life, accelerate lung function decline, generate high socioeconomic costs and increase the risk of death, especially exacerbations that require hospitalisation.2–5 Therefore, an important pillar in the management of COPD patients is the treatment of these exacerbations, which includes, among other measures, the use of assisted ventilation if there is severe respiratory failure.1

Until the 1980s, invasive mechanical ventilation (IMV) was the only option available for treating acute respiratory failure (ARF) refractory to conventional treatment, incurring significant morbidity and mortality6; thus, at the end of the 1980s, non-invasive mechanical ventilation (NIV) emerged as a potential alternative in patients with ARF.7,8

Since then, an increasing number of published studies have supported the use of NIV as the treatment of choice in patients with ARF (especially hypercapnic) due to acute COPD exacerbations, as it reduces the need for orotracheal intubation9–21 and its complications,20 mortality9–12,14,15,20 and hospital stay,9,11,15,16,19,20 improves clinical status and blood gases16,18,19 and reduces costs.22,23

In clinical practice, the use of NIV has varied over time,24,25 between hospitals24,26,27 and geographical regions,24,27 depending on the diagnosis26–28 and on the area or department of the hospital where the patient is located.28

All new healthcare technologies must be rigorously evaluated after its introduction into clinical practice to determine, among other aspects, whether it improves patient results (and to what extent) in terms of mortality, morbidity, quality of life and cost-effectiveness with respect to the previous technique, and to examine whether it meets clinical trial expectations regarding use, effectiveness and safety in routine practice.29,30 However, most of the studies on the implementation of this technology both in Spain and abroad are based on surveys among professionals25–28 and not on clinical information.

In 2009, the Bipap (Biphasic positive airway pressure) Programme for the Murcia Region was launched, with the aim of rationally introducing this new technology in all Murcia Health Service hospitals, standardising the criteria for use and providing adequate training. This study aims to assess the introduction of NIV and its impact on patients hospitalised for COPD exacerbation in the Murcia Region between 1997 and 2010.

This is a retrospective, observational study based on the Regional Registry Minimum Data Set for Acute Patients (MDS) of the Ministry of Health and Social Policy for the Murcia Region (MR).

This study is the first to analyse (using clinical-administrative databases) the introduction of NIV into routine clinical practice, of all patients treated for COPD exacerbation (more than 30000 discharges) in all public hospitals (9) of a geographical region (with 1500000 inhabitants) over a long period of time (14 years). Almost all the studies published in relation to this subject are based on surveys among professionals,25–28 and in fact we only found one similar study conducted in the United States12 on patients with COPD in a sample of hospitals during a 10-year period (1998–2008).

Although the hospital attendance of patients with COPD exacerbation decreased in the period studied, the use of NIV (12.1% of patients in the last year) showed an upward trend, which occurred at the expense of both the decrease in the patient group in which no ventilatory techniques were applied and in the IMV group, although in the latter case the change was not statistically significant: these same trends were observed when the annual percentage change in each group was studied (Fig. 3). The overall mortality (9.5% in the last year) and mortality in the patient group with no intervention showed an upward trend, although the change was not statistically significant in either case. It decreased in the intervention groups but only reached statistical significance in the NIV group. In summary, the introduction of NIV has been primarily directed towards those patients not previously ventilated, and its use has not affected the overall mortality.

Fig. 3.

COPD. Annual evolution by intervention group (%). Murcia region 1997–2010. NVI, no ventilatory intervention; NIV, non-invasive mechanical ventilation; IMV, invasive mechanical ventilation.

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The evolution of the use of NIV has followed a pattern similar to that expected: a gradual increase at the beginning that increased more strongly as the years passed and the technique became more consolidated, although no trend change was identified in any specific year. This situation, as in the American study,12 was accompanied by a decrease in the use of IMV, although this trend was not statistically significant in the present study. The proportion of patients with some type of ventilatory support was slightly lower than that observed in the aforementioned study (6.9% versus 8.1%). Of the ventilated patients, more than 60% were ventilated with NIV; this rate is higher than those described in the survey-based studies25,26,34 and in the first study mentioned,12 where only around 34% of ventilated patients were initially treated with NIV.

In comparison to the American study,12 it can be seen that the mortality rates in the patients treated with either non-invasive or invasive ventilation are similar. The mortality rates found for the group treated with NIV in both studies, as well as those described in another prospective, observational study on some 9000 patients with COPD conducted in the United Kingdom in 201135 are higher than those of clinical trials. This higher mortality in routine practice, which was observed particularly in the initial period in our case, could be explained by certain biases in the selection of the first patients treated with NIV, its use as ceiling treatment in very seriously ill patients or the learning curve of the technique, among other factors that the information source used did not record, and may be the reason for the decrease in mortality observed in the second seven-year period. In the American study,12 the mortality decreased significantly in the three patient groups, while in our case the behaviour was different, as the mortality decreased in the two intervention groups (without statistical significance in the IMV group), but not in the group of patients in whom no ventilatory technique was applied.

With the information available, the differences in the mortality trends cannot be explained by changes in the comorbidity of the patients. The mortality trend observed in the no-intervention group, together with the decrease in the population rates in this group over the years, seems to support the possible use of NIV in our region in less seriously ill patients who, prior to its introduction, were not treated with any type of ventilatory support.

The introduction of NIV does not appear to have notably influenced the mean patient stay.

The use of clinical-administrative databases, despite its advantages (availability of information, low costs, among others), also has limitations. Although the information available and the patients seem reasonably homogeneous, especially in the last 10 years of the study, it is obvious that the abovementioned source does not include relevant and accurate clinical information on the severity of the respiratory disease at the time of admission (blood gases), the patients’ previous clinical status, response to NIV treatment, or their location within the hospital (ICU admissions). Furthermore, by using the ICD-9-CM codes to identify patients with COPD, and to define the intervention groups, there may be some misclassification bias due to coding errors and/or changes in the coding standards which have occurred over the period.

The improvement in the information source used over the period studied does not appear to have influenced the results. An increase was observed in the completeness of the MBDS-HD, but information was available from the beginning on at least 90% of all patients treated for all causes. The improvement in the process for preparing discharge reports, based on the information contained in the MBDS-HD, and its coding results in an increase in the mean number of diagnoses and, consequently, the Charlson Index. The high correlation between these two indicators together with the small differences in the value of the Charlson Index between the intervention groups suggests that, rather than an increase in the complexity of the patients, there has been an improvement in the coding process. Moreover, it is clear that the Index does not have predictive value for the severity of the patient in terms of needing to use assisted ventilation or not.

In conclusion, this study appears to indicate that the introduction of NIV in the Murcia Region has primarily affected patients who would not previously have been placed on assisted ventilation. No improvement was noted in results, in terms of mortality or overall mean stay, linked to its introduction. Conducting studies with more accurate information sources (studies based on medical records, economic studies) would allow us to more accurately determine the benefits that NIV has brought to the treatment of these patients, and to redirect, if necessary, the indications for this technology in Murcian hospitals.

The authors work for the public healthcare system and have not received any financial assistance or grants from companies associated with these technologies. No external funding has been received for conducting this study.