However, these prodromal symptoms are also more likely to occur in people with two other autoimmune diseases — lupus and Crohn’s disease — and therefore, will not help earlier diagnosis, study investigator, Céline Louapre, professor of neurology, Sorbonne University and Paris Brain Institute, Paris, France, said in an interview.
“On the other hand, in certain patients who may be at particular risk of developing MS, such as in certain familial forms or in patients with incidental inflammatory lesions discovered on MRI, the presence of these symptoms could suggest an already active process, prior to the first typical symptoms of the disease,” she noted.
Retracing MS Origins
The case-control study, published online in Neurology, included 20,174 people with newly diagnosed MS who were matched to 54,790 without MS, as well as 30,477 with Crohn’s disease and 7337 with lupus.
Using International Classification of Diseases, 10th revision (ICD-10) codes in electronic health records, the researchers assessed the associations between 113 diseases and symptoms in the 5 years before and after an MS diagnosis.
Twelve ICD-10 codes were significantly positively associated with the risk for MS compared with controls without MS.
After considering ICD-10 codes suggestive of neurologic symptoms as the first diagnosis of MS, the following five ICD-10 codes remained significantly associated with MS:
- Depression (odds ratio [OR], 1.22; 95% CI, 1.11-1.34)
- Sexual dysfunction (OR, 1.47; 95% CI, 1.11-1.95)
- Constipation (OR, 1.5; 95% CI, 1.27-1.78)
- Cystitis (OR, 1.21; 95% CI, 1.05-1.39)
- UTIs of unspecified site (OR, 1.38; 95% CI, 1.18-1.61)
However, none of these conditions was selectively associated with MS in comparison with both lupus and Crohn’s disease. All five ICD-10 codes identified were still associated with MS during the 5 years after diagnosis.
“The importance of investigating prodromal signs in MS is that it allows us to retrace the origins of the disease,” said Dr. Louapre.
“The main contribution of the data on prodromes in MS is to clarify that the disease and its mechanisms are frequently underway well before the first typical neurological symptoms, and that the causes of MS are probably present many years before diagnosis,” she added.
A limitation of the study was that data were not available for other factors that could influence people’s risk of developing MS, such as education level, ethnicity, body mass index, socioeconomic status, or genetic information.
It also remains unclear whether the conditions linked to MS are risk factors for the disease or nonspecific early MS symptoms.
Preventing Disease Evolution
In a linked editorial, Ruth Ann Marrie, MD, PhD, with the University of Manitoba, Manitoba, Canada, and Raffaele Palladino, MD, PhD, with the University of Naples Federico II, Naples, Italy, note these findings highlight the challenges of accurately identifying the prodromal stage of a specific disease.
“Commonalities of prodromal features are recognized across neurodegenerative diseases; this is also true for immune-mediated diseases, and it is not surprising, given shared etiologic factors and pathobiological mechanisms,” they point out.
“This suggests that we should be trying to link prodromal features to specific underlying pathobiological changes rather than specific diseases. This approach would require use of different study designs, including broad, deeply phenotyped cohorts, but would allow us to develop and test interventions targeted at those mechanisms, and could ultimately achieve the goal of preventing disease evolution,” they add.
The study was supported by the French National Research Agency. Dr. Louapre has received consulting or travel fees from Biogen, Novartis, Roche, Sanofi, Teva, and Merck Serono, unrelated to this study. Dr. Marrie is a coinvestigator on studies receiving funding from Biogen Idec and Roche Canada; receives research funding from CIHR, Research Manitoba, Multiple Sclerosis Society of Canada, Multiple Sclerosis Scientific Foundation, Crohn’s and Colitis Canada, National Multiple Sclerosis Society, CMSC, the Arthritis Society and the US Department of Defense; and serves on the editorial board of Neurology. Dr. Palladino has taken part in advisory boards/consultancy for MSD and Sanofi and has received support from the UK MS Society.
A version of this article appeared on Medscape.com.