Identifying diagnostic markers in the health records of prediagnostic amyotrophic lateral sclerosis patients

<i>Objective</i>: Amyotrophic lateral sclerosis (ALS) has a poorly understood preclinical phase, particularly concerning diagnostic blood markers. Our objective was to determine whether distinct patterns in routinely collected clinical and laboratory markers exist during the preclinical phase and could be incorporated to facilitate early diagnosis. <i>Methods</i>: We conducted a longitudinal, retrospective, case-control study with health records of prediagnostic ALS patients (PDALS) from health maintenance organizations covering approximately 40% of the Israeli population. We included PDALS with at least 10 clinical visits and a minimal observation period of 36 months prior to the diagnosis date to measure differences between PDALS and controls and analyzed data from 1,810 adult individuals; 362 PDALS and 1,448 age- and sex-matched controls. <i>Results</i>: Significant differences were found in PDALS many months before the diagnosis date. These included biochemical parameters such as urea, creatinine, CK, calcium, iron, and liver enzymes, hematological values, and BMI. Some differences were detectable over 10 years prior to the diagnosis date. <i>Conclusions</i>: This study highlights the potential for early detection of ALS based on blood markers in the years preceding clinical diagnosis. These findings could significantly expedite diagnosis, identify individuals at risk for ALS, and uncover unrecognized disease mechanisms.