Factors associated with the number  of months of delaying in multiple sclerosis diagnosis: Comparison  of count regression models

Abolfazl Hosseinnataj; Roya Nikbakht; Seyed Nouraddin Mousavinasab; Sharareh Eskandarieh; Mohammad Ali Sahraian; Seyed Mohammad Baghbanian

doi:10.18502/cjn.v22i2.13330

Abolfazl Hosseinnataj Department of Biostatistics and Epidemiology, School of Health, Mazandaran University of Medical Sciences, Sari, Iran
Roya Nikbakht Department of Biostatistics and Epidemiology, School of Health, Mazandaran University of Medical Sciences, Sari, Iran
Seyed Nouraddin Mousavinasab Department of Biostatistics and Epidemiology, School of Health, Mazandaran University of Medical Sciences, Sari, Iran
Sharareh Eskandarieh Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
Mohammad Ali Sahraian Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
Seyed Mohammad Baghbanian Department of Neurology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran

DOI: https://doi.org/10.18502/cjn.v22i2.13330

Keywords: Multiple Sclerosis; Delayed Diagnosis; Iran; Disability Evaluation

Abstract

Background: It may take a long time to diagnose multiple sclerosis (MS) since the emergence of primary symptoms. This study aimed to use count regression models to compare their fit and to identify factors affecting delay in the diagnosis of MS.

Methods: Data were collected from the Nationwide MS Registry of Iran (NMSRI) for Mazandaran Province, Iran, using census sampling until April 2022. The four models of Poisson regression, negative binomial (NB) regression, zero-inflated Poisson (ZIP) regression, and zero-inflated negative binomial (ZINB) regression were used in this study.

Results: In this study on 2894 patients, 74.0% were women, and 8.5% had a family history of MS. The mean ± standard deviation (SD) of the patients’ age was 34.96 ± 9.41 years, and the mean delay in diagnosis was 12.32 ± 33.26 months, with a median of 0 (Q1-Q3: 0-9). The NB regression model showed the best performance, and factors, including a history of hospitalization and the year of symptom onset,
had significant effects on a delayed diagnosis. Besides, the Expanded Disability Status Scale (EDSS) score was significantly different before and after 2017; it was also associated with sex, type of MS, and history of hospitalization.

Conclusion: The mean diagnostic delay and the mean age of MS diagnosis are critical in Mazandaran Province.