Home invasive mechanical ventilation in Finland in 2015–2019

Discussion

The prevalence of HIMV in Finland was extremely low, diminishing during the 4-year follow-up. The average treatment periods were long, over 10 years. We found great variation in treatment lengths depending on the underlying diagnosis. As the treatment is long, even for the whole lifetime, it is noteworthy that since most patients are totally IMV-dependent they also need 24-h care, which is demanding and expensive. Despite this, most of the patients were able to live at home.

Many diseases, most commonly motor neurone disease, SCI and different muscular diseases, can lead to chronic hypoventilation and the need for HIMV treatment. Typical of these diseases is that they are currently incurable. The patients can also be divided into two categories: those with a disease leading to progressive respiratory failure and whose treatment is usually started electively, and those who failed to wean from mechanical ventilation after acute respiratory failure (e.g. SCIs) [5].

Few studies have examined the prevalence of HMV, and only a couple of countries have registers following HMV prevalence and treatment characteristics. The prevalence of HMV has been found to vary greatly between countries and also nationally [6]. In the Eurovent survey (2001–2002), the average prevalence of HMV was 6.6 in 100 000 [7]. Of these patients, 13% received invasive ventilation via tracheostomy, yielding a prevalence of 0.9 in 100 000, and the most common cause for HIMV was neuromuscular disease. The corresponding prevalence of HIMV in Australia and New Zealand was 0.5 in 100 000 [8] and in the United States 0.4 in 100 000 [9]. In Norway (2002–2007), the prevalence was 1.3 in 100 000 [4].

However, most of the earlier studies on the HIMV prevalence are over 10 years old, and therefore, current data are not available. Sweden and Norway have registers following HMV patients. According to the Swedevox data, the prevalence of HIMV patients in Sweden was 1.3 in 100 000 in 2018, but this is probably an underestimation. Patients especially with progressive neuromuscular disorder can convert from NIV to invasive ventilation without reporting the conversion to the registry. In addition, the coverage had been suboptimal during the last years (personal communication; Dr. Andreas Palm, Department of Medical Sciences, Respiratory, Allergy and Sleep Research, Uppsala, Sweden). Thus, we found the prevalence of HIMV in Finland to be similar to the Swedish results.

Reasons for the variation in prevalence are not fully known. Probably cultural and religious reasons explain some of the variation. Not all countries have precise definitions on when to initiate HMV, especially HIMV and this leaves more room for individual decision-making. Being married doubled the likelihood of proceeding to tracheostomy [10]. In addition, the caregivers’ attitudes, age under 65 years and the presence or absence of advanced planning might affect the patient's decision [10, 11]. In a Norwegian study, the treating physicians’ enthusiasm, knowledge and positive attitude towards HIMV were greater in the areas with high prevalence and these seemed to be important factors affecting the initiation of HIMV [6]. Moreover, regions with tertiary clinics that regularly followed the patients and densely populated areas seemed to have higher prevalence [8, 12]. Funding for the treatment varies largely. In some countries, like Finland and Japan, the government covers all expenses, but in other countries the economic burden is substantial for the patient [10]. One reason for Finland's higher prevalence might by the Finnish legislation that guarantees everyone the possibility for HIMV, including financing the expensive treatment. Neither do we impose age restrictions for the treatment. As mentioned already in introduction, in Finland, the treatment is always arranged by special medical care and funded by the government, so the patients should have no reason to arrange the treatment in for example private medical care. Neither does the private sector have knowledge of organising the demanding treatment. Thus, we believe, that no long-term HIMV patients should be missing from this study. Reasons for the Finnish national variation in prevalence are probably similar to the international reasons discussed above. The majority of Finns are evangelical Lutherans, but we did not study the possible effects of religious belief, civil or socioeconomic status on HIMV initiation in Finnish patients. We also acknowledge that the small number of patients may have an effect on our results, and part of the national variation could be explained by random variation.

The last study on ALS prevalence in Finland was done in 1983, when the prevalence was 6.4 in 100 000 [13]. According to our neurological authorities, the prevalence today is similar to that of Norway, 7.6 in 100 000. In our study, the prevalence of HIMV in ALS patients was 0.5 in 100 000. We found regional variation in the prevalence, from 1.6 in 100 000 in Oulu to 0.2 in 100 000 in Kuopio. About 5% of all Finnish ALS patients were tracheostomised and used life-support ventilation. Their survival was long; the mean treatment duration for all motor neurone patients was 7.7 years and for those who died, 9.0 years. Internationally, ALS prevalence was about 5.2–7.6/100 000 [14–16]. In Western countries, 1.5–5% of ALS patients underwent tracheostomy [17, 18], except in Italy, where the figure was 10.6% [19], and in Japan, even higher at about 30–39% [10, 18]. In other, older studies, median survival times after tracheostomy were shorter, from 0.7 to 6.2 years [10, 17, 19, 20]. Internationally, the majority of ALS HIMV patients have been male [16, 18, 19], but in our study the sex distribution was equal. HIMV treatment was started electively in only 34% of our patients. One possible explanation for the low proportion of elective IMV initiation is that about 3% of all ALS patients have respiratory-onset ALS. These patients are predominantly male, their survival times are shorter than in patients with bulbar or spinal onset ALS and their IMV start was more often unplanned [21].

The prevalence of our SCI patients has slightly increased; the prevalence was 0.4 in 100 000 in 2015 and 0.43 in 100 000 in 2019. The incidence of all SCIs in Finland was 9.2 in 100 000, the incidence of traumatic SCIs was 2.5–3.7 in 100 000 and the incidence of nontraumatic SCIs was 5.5 in 100 000 [22, 23]. In a Norwegian study, 0.4% of all SCI patients had HIMV, and the prevalence of HIMV was 0.2 in 100 000 [24]. During our 4-year follow-up SCI patients were the second largest group of new patients. Because SCI is an acute event, HIMV treatment is rarely initiated electively. The most common mechanisms for traumatic SCIs are traffic accidents and high falls in younger age groups and low falls in the elderly [23]. Decreasing the number of these accidents is challenging, and prevalence will likely remain similar. Very few studies exist on the survival of HIMV-treated SCI patients. In a British 25-year retrospective study, the mean survival of SCI patients with HIMV was 10.5 years, with younger patients surviving longer [25]. Our patients’ mean HIMV duration was 9.4 years and treatment duration of deceased patients was 7.4 years.

DMD and other muscular disease patients were among the youngest (average age 28.4 and 29.7 years) on HIMV treatment, initiation explained by the fact that DMD and other muscular diseases usually lead to chronic hypoventilation already in adolescence. This result is comparable to a Belgium study, where HIMV treatment started at an average age of 32.7 years [26]. The time from diagnosis to IMV initiation was long, about 20 years, so it is probable that NIV treatments, before proceeding to HIMV, were also lengthy. The treatment durations of DMD patients were long, an average of 11.0 years, and surviving patients were on average 40.3 years old on 1 January 2019. The lifetimes are comparable to other studies, where lifespan has ranged from 29 to 40 years [26–28]. In some studies, HIMV prolonged survival by 6–9 years, although some patients died because of complications associated with the tracheostomy tube [29].

The use of NIV treatment is growing rapidly. In Sweden in the 1990s and in Hong Kong at the beginning of 2000, the prevalence of HMV doubled over 5–6 years [8]. The technology of NIV treatment and mouthpiece ventilation has evolved, together with the knowledge of treating physicians, as the treatment has become more familiar [2, 14]. It seems that patients are surviving longer with NIV, and this is decreasing and postponing the initiation of HIMV. When comparing DMD patients’ survival on NIV and HIMV, no survival benefit over the other treatment was found [26, 27, 30]. However, the DMD Care Considerations Working Group guideline [31] (published in 2018) recommends NIV instead of tracheostomy to optimise the patient's quality of life. In our clinics, we also have the impression that DMD and other muscular disease patients are surviving longer with NIV and the prevalence of HIMV among them is decreasing. In ALS, NIV prolongs survival, especially in patients with better bulbar function, and low-quality evidence suggests that NIV maintains quality of life [32].

Our ALS patients’ treatment durations seems to be longer and in other disease groups at least equal to other studies [10, 19, 20, 28]. One explanation is that in Finland all HIMV patients are considered hospital patients and a registered nurse attends to the patient continuously. Therefore, treatment of the underlying disease for HIMV as well as other possible diseases are carefully managed. It is also possible that patients who decide to undergo tracheostomy are healthier and more motivated in treatments than nontracheostomised patients. According to our clinical experience, we try to base all HIMV initiations on careful planning; however, as we see in our results, most of the HIMV initiations are unplanned. This may be explained by the relatively large number of patients with SCI.