Model-Informed Precision Dosing Using Machine Learning for Levothyroxine in General Practice: Development, Validation and Clinical Simulation Trial.

Levothyroxine is one of the most prescribed drugs in the western world. Dosing is challenging due to high-interindividual differences in effective dosage and the narrow therapeutic window. Model-informed precision dosing (MIPD) using machine learning could assist general practitioners (GPs), but no such models exist for primary care. Furthermore, introduction of decision-support algorithms in healthcare is limited due to the substantial gap between developers and clinicians' perspectives. We report the development, validation, and a clinical simulation trial of the first MIPD application for primary care. Stable maintenance dosage of levothyroxine was the model target. The multiclass model generates predictions for individual patients, for different dosing classes. Random forest was trained and tested on a national primary care database (n = 19,004) with a final weighted AUC across dosing options of 0.71, even in subclinical hypothyroidism. TSH, fT4, weight, and age were most predictive. To assess the safety, feasibility, and clinical impact of MIPD for levothyroxine, we performed clinical simulation studies in GPs and compared MIPD to traditional prescription. Fifty-one GPs selected starting dosages for 20 primary hypothyroidism cases without and then with MIPD 2 weeks later. Overdosage and underdosage were defined as higher and lower than 12.5 µg relative to stable maintenance dosage. MIPD decreased overdosage in number (30.5 to 23.9%, P < 0.01) and magnitude (median 50 to 37.5 µg, P < 0.01) and increased optimal starting dosages (18.3 to 30.2%, P < 0.01). GPs considered lab results more often with MIPD and most would use the model frequently. This study demonstrates the clinical relevance, safety, and effectiveness of MIPD for levothyroxine in primary care.

Project Y: The search for clues explaining phenotype variability in MS.

BACKGROUND: To study phenotypic variability in MS patients, well-defined unbiased cohort studies are necessary. The most common and probably most important confounding factor when studying disease phenotype in MS is age. OBJECTIVE: To describe study design and subject characteristics of a unique birth cohort (Project Y). The overall aim of Project Y is to identify determinants associated with phenotypic variability in MS, eliminating the possibility of confounding by age. METHODS: Project Y is a population-based cross-sectional study of all people with MS born in the Netherlands in 1966. Patients and healthy controls were subjected to comprehensive examinations: functional and static imaging, physical and cognitive measurements, and lifestyle factors early and later in life. In addition body fluids were collected and stored for future biomarker research. RESULTS: 452 eligible MS patients were identified. Between December 2017 and January 2021, 367 MS patients and 125 healthy controls participated. The total number of identified cases results in a current prevalence of at least 189/100.000 for people born in the year 1966 in The Netherlands. CONCLUSION: Project Y is a unique cohort designed to identify factors associated with phenotypic variability in MS patients without the confounding effects of age. This first description of the Project Y cohort indicates that the prevalence of MS in the Netherlands might be higher than previously presumed. Various studies using Project Y data are ongoing and results will be published in upcoming years.

CD4+ T-Cell Responses Mediate Progressive Neurodegeneration in Experimental Ischemic Retinopathy.

Retinal ischemic events, which result from occlusion of the ocular vasculature share similar causes as those for central nervous system stroke and are among the most common cause of acute and irreversible vision loss in elderly patients. Currently, there is no established treatment, and the condition often leaves patients with seriously impaired vision or blindness. The immune system, particularly T-cell-mediated responses, is thought to be intricately involved, but the exact roles remain elusive. We found that acute ischemia-reperfusion injury to the retina induced a prolonged phase of retinal ganglion cell loss that continued to progress during 8 weeks after the procedure. This phase was accompanied by microglial activation and CD4+ T-cell infiltration into the retina. Adoptive transfer of CD4+ T cells isolated from diseased mice exacerbated retinal ganglion cell loss in mice with retinal reperfusion damage. On the other hand, T-cell deficiency or administration of T-cell or interferon-γ-neutralizing antibody attenuated retinal ganglion cell degeneration and retinal function loss after injury. These findings demonstrate a crucial role for T-cell-mediated responses in the pathogenesis of neural ischemia. These findings point to novel therapeutic targets of limiting or preventing neuron and function loss for currently untreatable conditions of optic neuropathy and/or central nervous system ischemic stroke.

The natalizumab wearing-off effect: End of natalizumab cycle, recurrence of MS symptoms.

OBJECTIVE: Natalizumab is effective in treating relapsing-remitting multiple sclerosis (RRMS). However, many patients report an increase of multiple sclerosis symptoms at the end of the natalizumab cycle: a wearing-off effect. The objective of this study was to evaluate the prevalence of the wearing-off effect in patients with standard and extended intervals and to study possible associations with pharmacokinetic/dynamic measurements and patient characteristics in a prospective, monocenter, cross-sectional cohort study. METHODS: Patients with RRMS, with a minimum of 6 natalizumab infusions, were asked to complete 3 questionnaires: the Multiple Sclerosis Impact Scale, the 36-Item Short Form Health Survey, and a general questionnaire regarding the wearing-off effect. Natalizumab concentration and α4-integrin receptor saturation were measured before redosing. RESULTS: Ninety-three patients were included. A total of 54% experienced a wearing-off effect during natalizumab treatment and 32% experienced a current wearing-off effect at time of measurement. The self-reported wearing-off effect was not associated with natalizumab concentration nor with α4-integrin receptor saturation. The wearing-off effect was more frequently reported in the standard interval group (39%) than in the extended interval group (19%); the duration of symptoms was comparable between both groups. The wearing-off effect was not associated with number of infusions, disease duration, age, or sex. CONCLUSION: The wearing-off effect is a frequently reported phenomenon but is unlikely to reflect a nonoptimal pharmacokinetic/dynamic state. We did not find risk factors predicting the wearing-off effect.