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BRIEF COMMUNICATIONS: Eric J. Sorenson, Andrew P. Stalker, Leonard T. Kurland, and Anthony J. Windebank Amyotrophic lateral sclerosis in Olmsted County, Minnesota, 1925 to 1998 Neurology 2002; 59: 280-282 [Abstract] [Full text] [PDF]

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Reply to Letter to the Editor

Eric J. Sorenson, Andrew P. Stalker, Leonard T. Kurland and Anthony J. Windebank   (3 February 2003)

Amyotrophic lateral sclerosis in Olmsted County, Minnesota, 1925 to 1998

Adriano Chio, Gabriele Mora, Roberto Mutani, and Davide Schiffer   (3 February 2003)

Increase in survival in patients with amyotrophic lateral sclerosis between 1971 and 1998.

Daniela Testa, Graziella Filippini   (3 February 2003)

Reply to Letter to the Editor 3 February 2003
Eric J. Sorenson Mayo Clinic Rochester, MN, Andrew P. Stalker, Leonard T. Kurland and Anthony J. Windebank Send Correspondence to journal: Re: Reply to Letter to the Editor Sorenson.Eric{at}mayo.edu Eric J. Sorenson, et al.	We thank Chiņ et al. for their interest in our recent article. While the main emphasis of the article is that the incidence rates as a whole have not changed over time, we agree that the lower incidence rate of ALS in the aged is interesting. One has to be cautious in interpreting this trend. The numbers of these over the age of 70 were small and the 95% confidence intervals while separate were very close. While this trend does not confirm or support any specific etiology or pathophysiology, it does suggest that there is a finite period of risk. Age at symptomatic presentation likely depends upon two variables: Time of disease inception followed by a latency period until symptoms emerge. Given the wide age distribution of the disease, it is necessary that one or both of the variables is/are not constant. To account for the drop in incidence in the aged, however both must have upper limits. This model agrees with the experience of the SOD1 mutations where the time of disease inception is at conception followed by a variable latency period. In this example time of inception is constant but the latency varies, determined largely upon which mutation is present. It is possible that the time of inception may vary. However, there is likely an age beyond which either exposure doesn't occur (eg. genetic factors after conception) or exposure occurs without the risk (eg. exposure to an environmental agent at a certain period of development may cause the disease but exposure at a later date does not). Which of these is most relevant to the drop in disease incidence in the aged cannot be answered today.
Amyotrophic lateral sclerosis in Olmsted County, Minnesota, 1925 to 1998 3 February 2003
Adriano Chio University of Turin and San Giovanni Battista Hospital Italy, Gabriele Mora, Roberto Mutani, and Davide Schiffer Send Correspondence to journal: Re: Amyotrophic lateral sclerosis in Olmsted County, Minnesota, 1925 to 1998 achio{at}usa.net Adriano Chio, et al.	We read with interest the recent article by Sorenson et al. [1], which extended the previous surveys on the epidemiology of amyotrophic lateral sclerosis in Rochester, Minnesota. [2] The authors utilized the well-known Rochester Epidemiologic Project to identify all subjects resident in Olmsted County diagnosed with ALS between 1925 and 1998. Interestingly, they found that the incidence rates of ALS did not significantly change during the examined period, and the mean annual incidence rate was similar to that found in recent studies based on epidemiological registers in Europe, [3, 4] confirming the idea of an uniform distribution of ALS in western countries. A previous study performed in the same area in the period 1925-1984 found a progressive increase of age-specific ALS incidence rates with advancing age. [2] Although not confirmed in other studies, this observation has been one of the most powerful indications of the neurodegenerative nature of ALS. Sorenson et al. [1] now found that extending the data to the two last decades, the age-specific incidence rates showed a progressive increase with age up to the seventh decade, but markedly decreased in older age groups. This trend is again similar to that observed in most epidemiological studies performed both in the United States and in Europe, [3] and, if confirmed, may have major implications on the current perspective of the pathogenesis of ALS. In fact, if age- specific incidence rates increase with age at all ages, then ALS would be considered an aging-dependent disease (such as Parkinson and Alzheimer diseases), likely to be related to a degenerative process, of the entropic type, involving neuron or glia metabolism. [4] Conversely, if age-specific incidence has a peak in a given decade (the seventh decade in Sorenson et al study), [2] it would suggest that ALS is a age-dependent (or age- related) disease, with a critical age period of susceptibility (such as, for example, multiple sclerosis), implying the role of an environmental agent or a genetic basis for ALS. [5] References 1. Sorenson EJ, Stalker AP, Kurland LT, Windebank AJ. Amyotrophic lateral sclerosis in Olmsted County, Minnesota, 1925 to 1998. Neurology 2002; 59:280-282. 2. Yoshida S, Mulder DW, Kurland LT, Chu C-P, Okazaki H. Follow-up study on amyotrophic lateral sclerosis in Rochester, Minn., 1925 through 1984. Neuroepidemiology 1986; 5:61-70. 3. Piemonte and Valle d'Aosta Register for ALS (PARALS). Incidence of ALS in Italy. Evidence for a uniform frequency in Western countries. Neurology 2001;56:239-244. 4. Dani SU, Hori A, Walter GF. Principles of neural aging. Amsterdam, Alsevier, 1997. 5. Brody JA, Grant MD. Age-associated diseases and conditions: implications for decreasing late life morbidity. Aging Clin Exp Res 2001: 13:64-67.
Increase in survival in patients with amyotrophic lateral sclerosis between 1971 and 1998. 3 February 2003
Daniela Testa, Neurology Istituto Nazionale Neurologico C. Besta Milano (italy), Graziella Filippini Send Correspondence to journal: Re: Increase in survival in patients with amyotrophic lateral sclerosis between 1971 and 1998. dtesta{at}istituto-besta.it Daniela Testa, et al.	In their study of the incidence of ALS in Olmsted County US from 1925 to 1998, Sorenson et al. (1) found no change in survival over the study period, despite increasing use of percutaneous endoscopic gastrostomy (PEG), non-invasive ventilator assistance (NIV), and riluzole therapy after 1990. We examined the survival of 793 patients discharged from our Institute from 1971 to 1998 with a diagnosis of probable or definite ALS according to the El Escorial criteria. For each patient included, vital status on 31 July, 2001 was assessed through the Local Records Offices of the towns of residence. Only three cases were lost to follow-up. After stratification into three cohorts according to date of diagnosis (table) we found that survival increased significantly over the 28-year period. Age at disease onset, age at diagnosis, age at death, sex ratio, and frequency of type of onset (spinal or bulbar) did not differ between the cohorts. This increase in survival may be due to improved palliative care in Italy, including the use of NIV and PEG. (2,3) Several studies referred to in the research recommendations of the Subcommittee of the American Academy of Neurology also suggest longer survival due to improved palliative care. (4) Table: Survival from diagnosis of 790 ALS patients diagnosed in 1971-89, 1980-89 and 1990-98 Years 1971-79 1980-89 1990-98 No. of patients 177 284 329 Median survival(years)*1.31 1.79 1.69 95% confidence interval 1.17-1.45 1.55-2.02 1.95-2.21 3-year survival (%) 18 28 34 5-year survival (%) 5 15 19 *Kaplan Meyer survival curves: log-rank p<0.001 References 1. Sorenson EJ, Stalker AP, Kurland LT, Windebank AJ. Amyotrophic lateral sclerosis in Olmsted County, Minnesota, 1925 to 1998. Neurology 2002;59(2):280-282. 2. Mazzini L, Corra T, Zaccala M, Mora G, Del Piano M, Galante M. Percutaneous endoscopic gastrostomy and enteral nutrition in amyotrophic lateral sclerosis. J Neurol 1995;242(10):695-698. 3. Chio A, Silani V; Italian ALS Study Group. Amyotrophic lateral sclerosis care in Italy: a nationwide study in neurological centers. J Neurol Sci 2001;191:145-150. 4. Miller RG, Rosenberg JA, Gelinas DF, Mitsumoto H, Newman D, Sufit R, Borasio GD, Bradley WG, Bromberg MB, Brooks BR, Kasarskis EJ, Munsat TL, Oppenheimer EA. Practice parameter: the care of the patient with amyotrophic lateral sclerosis (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology: ALS Practice Parameters Task Force. Neurology 1999;52(7):1311-1323.