Use of respiratory function tests to predict survival in amyotrophic lateral sclerosis

Sniff nasal inspiratory pressure as a prognostic factor of tracheostomy or death in amyotrophic lateral sclerosis

Forced vital capacity (FVC) shows limitations in detecting respiratory failure in the early phase of amyotrophic lateral sclerosis (ALS). In fact, mild-to-moderate respiratory muscle weakness may be present even when FVC is normal, and ALS patients with bulbar involvement might not be able to perform correctly the spirometry test. Sniff nasal inspiratory pressure (SNIP) is correlated with transdiaphragmatic strength. We evaluated SNIP at baseline as a prognostic factor of tracheostomy or death in patients with ALS. In a multidisciplinary tertiary care center for motorneuron disease, we enrolled 100 patients with ALS diagnosed with El Escorial criteria in the period between January 2006 and December 2010. Main outcome measures were tracheostomy or death. RECursive Partitioning and AMalgamation (RECPAM) analysis was also used to identify subgroups at different risks for the tracheostomy or death. Twenty-nine patients with ALS reached the outcome (12 died and 17 had tracheostomy). Using a multivariate model SNIP correctly classified the risk of the composite event within 1 year of follow-up with a continuous Net Reclassification Improvement cNRI of 0.58 (p = 0.03). Sex, Amyotrophic Lateral Sclerosis Functional Rating Scale revisited, site of onset, and FVC did not improve the classification of prognostic classes. SNIP ≤18 cmH2O identified the RECPAM class with the highest risk (Class 1, hazard ratio = 9.85, 95 % confidence interval: 2.67-36.29, p < 0.001). SNIP measured at baseline identified patients with ALS with initial respiratory failure. Finally, using only ALS patients with spinal onset of the disease, our findings were mostly overlapping with those reported in the models including the whole sample. At baseline, SNIP appeared to be the best predictor of death or tracheostomy within 1 year of follow-up. The measurement of SNIP in the early phase of the disease may contribute to identify patients with high risk of mortality or intubation. SNIP may also provide an additional tool for baseline stratification of patients with ALS in clinical trials.

Quantifying disease progression in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) exhibits characteristic variability of onset and rate of disease progression, with inherent clinical heterogeneity making disease quantitation difficult. Recent advances in understanding pathogenic mechanisms linked to the development of ALS impose an increasing need to develop strategies to predict and more objectively measure disease progression. This review explores phenotypic and genetic determinants of disease progression in ALS, and examines established and evolving biomarkers that may contribute to robust measurement in longitudinal clinical studies. With targeted neuroprotective strategies on the horizon, developing efficiencies in clinical trial design may facilitate timely entry of novel treatments into the clinic.

Rates of progression of weight and forced vital capacity as relevant measurement to adapt amyotrophic lateral sclerosis management for patient Result of a French multicentre cohort survey

OBJECTIVES

To compare survival, to describe the progression of anthropometry, pulmonary capacity and functioning in ALS (Amyotrophic Lateral Sclerosis) and to identify the most relevant variables to adapt ALS management for patients.

METHODS

A cohort study was performed in French ALS centres between January 2003 and July 2005. Eligible patients were treated by Riluzole and had a slow vital capacity (SVC) or a forced vital capacity (FVC) at least equal to 60%. Demographic, medical and ALS characteristics were registered. Manual Muscular Testing (MMT) and ALS Functional Rating Scale (ALSFRS) were performed. Kaplan Meier method was used to analyse survival. ALS progression was measured by the percentage weight, FVC, SVC, MMT and ALSFRS loss and was analysed as longitudinal data using mixed model.

RESULTS

Three hundred and eighty three patients were included. The median survival since ALS diagnosis was 2.34 years (95%CI 2.10-2.65). Mixed model analyses revealed a more significant worsening progression of weight and FVC loss for bulbar onset. The drop of ALSFRS and SVC is similar whatever the ALS forms.

CONCLUSIONS

Rates of progression of weight and FVC should be regularly watched over to support neurologists to adapt ALS management for patients.

Riluzole and prognostic factors in amyotrophic lateral sclerosis long-term and short-term survival: a population-based study of 1149 cases in Taiwan

Background

Amyotrophic lateral sclerosis (ALS) is a rare disease in Taiwan; thus, estimation of ALS mortality is difficult. We evaluated factors associated with ALS survival in Taiwan.

Methods

The study enrolled 1149 Taiwanese with a primary diagnosis of ALS during 1999–2008. Follow-up information was available for all patients; mean (SD) duration of follow-up was 2.91 (2.62) years. Medical interventions, including noninvasive positive pressure ventilation (NIPPV), tracheotomy, gastrostomy, and riluzole, were included in time-dependent survival analysis.

Results

Of the 1149 ALS patients, 438 (38.12%) died during follow-up. Mortality in the first year was 16%, which was 13 times (95% CI 11.1–15.2) the age- and sex-standardized rate of the general population in Taiwan. The average annual crude mortality rate was 13.1% (person-years). Factors significantly associated with increased mortality were male sex, advanced age, rural residence, lower economic status, no tracheotomy, and no riluzole treatment. Significant predictors of long-term versus average survival were younger age at diagnosis, being a dependent or receiving social welfare, and NIPPV support. Significant predictors of short-term versus average survival were older age, being employed, no tracheotomy, and no riluzole use.

Conclusions

The results support the use of riluzole to improve ALS survival. Patients who received riluzole and underwent tracheotomy had the best survival.

The Role of immune and inflammatory mechanisms in ALS

Amyotrophic lateral sclerosis (ALS) is a severe progressive neurodegenerative disease. The cause is unknown, but genetic abnormalities have been identified in subjects with familial ALS and also in subjects with sporadic ALS. Environmental factors such as occupational exposure have been shown to be risk factors for the development of ALS. Patients differ in their clinical features and differ in the clinical course of disease. Immune abnormalities have been found in the central nervous system by pathological studies and also in the blood and CSF of subjects with ALS. Inflammation and immune abnormalities are also found in animals with a model of ALS due to mutations in the SOD1 gene. Previously it has been considered that immune abnormalities might contribute to the pathogenesis of disease. However more recently it has become apparent that an immune response can occur as a response to damage to the nervous system and this can be protective.

Assessment of respiratory functions by spirometry and phrenic nerve studies in patients of amyotrophic lateral sclerosis

OBJECTIVE

Spirometry is the most common test recommended to monitor respiratory dysfunction in patients of amyotrophic lateral sclerosis (ALS). However, the test depends on the patient's efforts and may be difficult to conduct in patients with faciobulbar weakness. We aimed to study the role of phrenic nerve-electrophysiological studies to predict respiratory dysfunction and correlate it with the forced vital capacity (FVC) in patients of ALS.

METHODS

Forty-three unselected patients (32 male, 25 with limb-onset ALS, age 50±15 years) with clinically definite or probable ALS were included. They were evaluated at entry and after a period of 6 months with the ALS functional rating scale (ALSFRS), their respiratory subscores (ALS-FRSr), their FVC values as determined by spirometry, and phrenic nerve studies.

RESULTS

Six patients could not perform a satisfactory spirometry at the onset and during the course of illness. All the six patients had severe faciobulbar weakness. Respiratory abnormalities on spirometry were found in 85% of patients, whereas only 30% were symptomatic for respiratory dysfunction. In patients with severe respiratory dysfunction (FVC<60%), the phrenic nerve motor amplitudes (PNAMPs) were significantly reduced compared to those with mild-to-moderate respiratory dysfunction (FVC≥60%). The FVC value showed a significant correlation with the PN-AMP. Nine patients had a poor outcome (death or severe disability) at the end of a period of 6 months. Low levels of both FVC and PN-AMP were predictors of poor outcome for patients at the end of 6 months.

CONCLUSION

We conclude that respiratory dysfunction, as determined by spirometry, is common in patients of ALS. However, only about one-third of patients show symptoms of respiratory distress. Clinical symptoms of respiratory distress are unreliable predictors of respiratory failure in ALS. Measurement of PN-AMP at the time of presentation may be an additional tool to assess respiratory dysfunction in ALS. Reduced PN-AMP values may be indicative of low FVC and may have some role in the assessment of respiratory function in patients in whom a routine spirometry is not possible due to limitations arising from the illness. Both low FVC and reduced PN-AMP at the time of presentation are predictors of poor outcome for patients at the end of 6 months.

Management of respiratory symptoms in ALS

Respiratory insufficiency is a frequent feature of ALS and is present in almost all cases at some stage of the illness. It is the commonest cause of death in ALS. FVC is used as important endpoint in many clinical trials, and in decision-making events for patients with ALS, although there are limitations to its predictive utility. There are multiple causes of respiratory muscle failure, all of which act to produce a progressive decline in pulmonary function. Diaphragmatic fatigue and weakness, coupled with respiratory muscle weakness, lead to reduced lung compliance and atelectasis. Increased secretions increase the risk of aspiration pneumonia, which further compromises respiratory function. Bulbar dysfunction can lead to nutritional deficiency, which in turn increases the fatigue of respiratory muscles. Early recognition of respiratory decline and symptomatic intervention, including non-invasive ventilation can significantly enhance both quality of life and life expectancy in ALS. Patients with respiratory failure should be advised to consider an advance directive to avoid emergency mechanical ventilation.