Prolactin is Not Associated with Disability and Clinical Forms in Patients with Multiple Sclerosis
An association between prolactinemia with disability, clinical forms, and sex of patients with multiple sclerosis (MS) remains unclear. The aim of this study was to evaluate the association of prolactin with clinical forms and accumulating disability over time in patients with MS. A longitudinal study was carried out with 101 patients with relapsing–remitting MS (RRMS) and 19 with progressive forms of MS (ProgMS). The disability over time, as well as prolactin and ferritin serum levels were evaluated at baseline (T0), 8-month follow-up (T8), and 16-month follow-up. The disability at T0, T8, and T16 was higher among patients with ProgMS than those with RRMS. Prolactin and ferritin levels did not differ over time between both groups. Initially, prolactin was associated with MS disability. After introducing age and sex, the effects of prolactin on disability were no longer significant. Prolactin was associated with age and sex, whereby age was positively associated with disability. In the same way, after introducing age and sex, the effects of diagnosis on prolactin levels, as well as the association between prolactin and ferritin, were no longer significant (P = 0.563 and P = 0.599, respectively). Moreover, 21.6% of the variance in the disability was predicted by age (P < 0.001), and sex (P = 0.049), while prolactin was not significant. In conclusion, the effects of prolactin on the disability and clinical forms of MS patients may be spurious results because those correlations reflect the positive associations of age with the disability and the negative association of age with prolactin.
KeywordsMultiple sclerosis Disability Prolactin Ferritin Spurious result
This study was partially supported by Novartis Biosciences S.A. for the development of the research according to the Researcher’s Initiative Study CFTY720DBR07T. The authors do not receive any reimbursement or financial benefits and declare that they have no competing interests. Novartis Biosciences S.A. played no role in the design, methods, data management or analysis or in the decision to publish. The study was also supported by grants from Coordination for the Improvement of Higher Level of Education Personnel (CAPES) of Brazilian Ministry of Education; Institutional Program for Scientific Initiation Scholarship (PIBIC) of the National Council for Scientific and Technological Development (CNPq).
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
The protocol was approved by the Institutional Research Ethics Committees of University of Londrina, Paraná, Brazil (CAAE: 22290913.9.0000.5231) and all of the individuals invited were informed in detail about the research and gave written Informed Consent.
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