Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Jul;12(4):272-7.
doi: 10.3109/17482968.2011.577786. Epub 2011 May 9.

Advanced statistical methods to study the effects of gastric tube and non-invasive ventilation on functional decline and survival in amyotrophic lateral sclerosis

Nazem Atassi  1 , Merit E Cudkowicz, David A Schoenfeld
Affiliations

Advanced statistical methods to study the effects of gastric tube and non-invasive ventilation on functional decline and survival in amyotrophic lateral sclerosis

Nazem Atassi et al. Amyotroph Lateral Scler. 2011 Jul.

Abstract

A few studies suggest that non-invasive ventilation (1) and gastric tube (G-tube) may have a positive impact on survival but the effect on functional decline is unclear. Confounding by indication may have produced biased estimates of the benefit seen in some of these retrospective studies. The objective of this study was to evaluate the effects of G-tube and NIV on survival and functional decline using advanced statistical models that adjust for confounding by indications. A database of 331 subjects enrolled in previous clinical trials in ALS was available for analysis. Marginal structural models (MSM) were used to compare the mortality hazards and ALSFRS-R slopes between treatment and non-treatment groups, after adjusting for confounding by indication. Results showed that the placement of a G-tube was associated with an additional 1.42 units/month decline in the ALSFRS-R slope (p < 0.0001) and increased mortality hazard of 0.28 (p = 0.02). The use of NIV had no significant effect on ALSFRS-R decline or mortality. In conclusion, marginal structural models can be used to adjust for confounding by indication in retrospective ALS studies. G-tube placement could be followed by a faster rate of functional decline and increased mortality. Our results may suffer from some of the limitations of retrospective analyses.

PubMed Disclaimer

Conflict of interest statement

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Figures

Figure 1
Figure 1
Generalized estimating equation models (GEE): an illustration of the effect of NIV on ALSFRS-R slope without controlling for confounding by indication.
Figure 2
Figure 2
Marginal structural models (MSM): an illustration that the negative effect of NIV seen using the routine GEE models is no longer there after correcting for confounding by indication.
See this image and copyright information in PMC

References

    1. Chicago Uo. Ceftriaxone as effective therapy in refractory Lyme disease. The Journal of Infectious Diseases. 1987;155:1322–1324. - PubMed
    1. Brooks BR. Natural history of ALS. Neurology. 1996;47 Suppl 2:S71–S82. - PubMed
    1. Del Piano M, Occhipinti P, Orsello M, Balare M. Percutaneous endoscopic gastrostomy (PEG) reduces complications and improves survival in amyotrophic lateral sclerosis (ALS) Gastrointest Endosc. 1999;49:192. - PubMed
    1. Mazzini L, Corrá T, Zaccala M, Mora G, Del Piano M, Galante M. Percutaneous endoscopic gastrostomy and enteral nutrition in amyotrophic lateral sclerosis. J Neurol Neurosurg Psychiatry. 1995;242:695–698. - PubMed
    1. Desport JC, Preux PM, Truong CT, Courat L, Vallat JM, Couratier P. Nutritional assessment and survival in ALS patients. Amyotroph Lateral Scler Other Motor Neuron Disord. 2000;2:91–96. - PubMed

Publication types