Neurology -- Correspondence for del Aguila et al., 60 (5) 813-819

Correspondence published:

Prognosis in amyotrophic lateral sclerosis: A population-based study: Adriano Chio, Roberto Mutani and Gabriele Mora (16 July 2003)

Reply to Letter to the Editor: WT Longstreth, MA del Aguila (16 July 2003)

Prognosis in amyotrophic lateral sclerosis: A population-based study 16 July 2003

Adriano Chio,
Department of Neurosciences
Via Cherasco 15 Torino Italy 10126,
Roberto Mutani and Gabriele Mora
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Re: Prognosis in amyotrophic lateral sclerosis: A population-based study

achio{at}usa.net Adriano Chio, et al.

We read with interest the article by del Aguila et al., [1] which assessed the factors related to outcome in a population-based series of ALS patients. They found that marital status has a significant independent effect on survival. This finding may be related to a better quality of care in patients living with their wife/husband, and is consistent with the observation that ALS prognosis is related to perceived QoL, in turn strongly correlated to the patients’ satisfaction for the support they receive from family and social network, [2] and with the observation of the relevant role of psychological well-being on survival in ALS. [3] These observations, taken together, indicate the importance of considering psychosocial variables in the caring of ALS patients and, perhaps, in the planning of clinical trials.
However, the authors did not consider some important factors that are likely to modify the prognosis of ALS patients, namely respiratory status, enteral nutrition, non invasive ventilation (NIV), therapy with riluzole, and attending an ALS Clinic.
Respiratory status at the time of diagnosis, measured with forced vital capacity (expressed as percent of predicted), was the strongest single prognostic factor in ALS in a recent population-based study, enteral nutrition also entered was the final prognostic model. [4] Moreover, in our experience, the acceptance of enteral nutrition is strongly influenced by social and marital status and, to a lesser extent, by economic conditions. Similar considerations can be done with NIV. Since marital status, and maybe race, may have a strong influence on the decision to underwent these procedures, the findings by del Aguila et al. [1] may be at least in part related to the lack of inclusion of these therapeutic variables in the initial model.
Also the independent effect of riluzole on ALS survival has been demonstrated in two population-based studies. [4, 5] Finally, a recent paper observed that attending or not an ALS clinic has a major affect on ALS survival. [5] This aspect could in part account for the differential survival in subjects living in King county (which includes the city of Seattle) versus other areas examined in the Washington study. [1]
In our opinion, all factors modifying ALS prognosis, such as respiratory function, enteral nutrition, NIV or attending an ALS Clinic, should be considered when planning trials for testing potential benefits of new drugs in ALS.
References:
1.del Aguila MA, Longstreth WT, Jr, McGuire V, Koepsell TD, van Belle G. Prognosis in amyotrophic lateral sclerosis. A population-based study. Neurology 2003; 60: 813-819.
2.Chiò A, Gauthier A, Montuschi A, Di Vito N, Calvo A, Mutani R. Quality of life in ALS: Cross-sectional analysis of determinants and effect on outcome. Neurology 2003; 60 (Suppl 1): A166.
3.McDonald E, Wiedenfeld SA, Hillel A, Carpenter CL, Walter RA. Survival in amyotrophic lateral sclerosis. The role of psychological factors. Arch Neurol 1994; 51:17-23.
4.Chiò A, Mora G, Leone M, Mazzini L, Cocito D, Giordana MT, Bottacchi E, Mutani R, for the Piemonte and Valle d’Aosta Register for ALS. Neurology 2002; 59: 99-103.
5. Traynor BJ, Alexander M, Corr B, Frost E, Hardiman O. An outcome study of riluzole in amyotrophic lateral sclerosis. A population-based study in Ireland, 1996-2000. J Neurol 2003; 250: 473-479.

Reply to Letter to the Editor 16 July 2003

WT Longstreth,
Harborview Medical Center
325 Ninth Avenue Seattle WA 98104-2420,
MA del Aguila
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Re: Reply to Letter to the Editor

wl{at}u.washington.edu WT Longstreth, et al.

We appreciate the comments from Chiò et al. and applaud their work in this field. Given the previous observations about quality of life and survival, we had expected to find more associations than we observed between survival and the eight dimensions and two summary scores on the Medical Outcomes Study Short Form 36 (SF-36). Although a significant association was found for the "Social Function" dimension, when all eight dimensions competed in a multivariable model, "Physical Function" dimension dominated, and "Social Function" did not enter. Perhaps some other measure of psychological well-being would have yielded different results.
This study focused on prognostic factors available around the time of diagnosis. Consequently, we did not include in these analyses information on use of gastrostomy tubes and non-invasive ventilation. Confounding by indication makes difficult predictions about the effects on survival of these and other interventions. Also, in a recent Cochrane review, authors estimated riluzole prolongs survival by about two months and questioned its utility in older patients and patients with advanced disease. [1] In a recent report from the Mayo Clinic, survival was not significantly different for those diagnosed before 1990, when few if any had gastrostomy tubes, non-invasive ventilation or riluzole, and those diagnosed in 1990 and after. [2] Similarly, in a recent abstract describing the
Scottish Motor Neuron Disease registry, investigators documented a decline in median survival between the first (1889-1993) and second (1994- 1998) half of the study period. [3]
Although clinics specializing in neuromuscular diseases existed in the three counties during the study period, no clinic specialized solely in ALS. In addition, others have demonstrated a survival bias in patients seen in referral clinics perhaps reflecting less aggressive disease in those who remain able to travel to such clinics. [4, 5]
We agree with Chiò et al. that a careful assessment of prognostic factors may allow for more efficient evaluations of treatments.
References:
1.Miller RG, Mitchell JD, Lyon M, Moore DH. Riluzole for amyotrophic lateral sclerosis (ALS)/motor neuron disease (MND) (Cochrane Review). The Cochrane Library. Oxford: Update Softeware; 2003 (2).
2.Sorenson EJ, Stalker AP, Kurland LT, Windebank AJ. Amyotrophic lateral sclerosis in Olmsted County, Minnesota, 1925 to 1998. Neurology 2002;59:280-282.
3.Forbes RB, Colville S, Parratt J, Chancellor A, Davenport R, Swingler RJ. Ten-year survival data from the Scottish MND Registry (abstract). J Neurol Neurosurg Psychiatry 2002;73:217.
4.Juergens SM, Kurland LT, Okazaki H, Mulder DW. ALS in Rochester, Minnesota, 1925-1977. Neurology 1980;30:463-470.
5.Lee JR, Annegers JF, Appel SH. Prognosis of amyotrophic lateral sclerosis and the effect of referral selection. J Neurol Sci 1995;132:207- 215.