Diagnosis — Diagnosing SPMS can be difficult because it relies entirely on clinical judgement. (1) There are no clear diagnostic criteria, and patients may not notice a symptomatic change during the early stages of SPMS because of the brain’s ability to compensate for the loss of neurons. For this reason, diagnosis may be delayed up to three years and is often given retrospectively.(2)
Efforts have been made to improve SPMS diagnostics. Screening tools, including the MS Progression Discussion Tool, the MS prediction score and the SPMS nomogram have been developed to leverage data to predict the risk of progression and diagnose early-stage SPMS accurately. Newer imaging technologies, such as unconventional MRIs and optical coherence tomography, may provide higher sensitivity biomarker measurements to aid in detecting disease risk and progression. (2) Emerging biomarkers, measured by either images or tests of cerebral spinal fluid or blood, include neurofilament light chain levels in serum or cerebrospinal fluid (CSF), CSF sCD27, chemokine (C-C motif) ligand 18 plasma levels, the MS risk allele HLA-DRB1*15 and chitinase-3-like protein (1). Larger-scale trials are needed for further data generation before these markers can be used clinically. (1,2)
Once diagnosed, SPMS is further categorized into active and nonactive disease states. First established in 2013, the term “active” is defined as relapses, acute or subacute episodes of new or increasing neurologic dysfunction followed by full or partial recovery, in the absence of fever or infection and/or the occurrence of contrast-enhancing T1 hyperintense or new or unequivocally enlarging T2 hyperintense lesions. A clinical assessment for disease activity is recommended annually. (5)
Disability and comorbidities — With SPMS, patients experience cognitive and physical decline, such as sleep changes, fatigue, incontinence, sexual dysfunction, and spasticity. Spasticity typically increases with disease progression and can eventually become refractory. (6) Disability associated with MS, which is primarily measured by the ability to walk, can substantially affect patient quality of life and socioeconomic status. (6) Disability progression is typically influenced most by the duration of disease; this differs from the disability progression associated with other diseases, which is often most influenced by patient age. (7) Adjusting to disability and other decline can be difficult and stressful for patients. Key determinants for a successful adjustment involve developing healthy coping strategies, participating in patient support networks and maintaining appropriate activity levels.(8)
In addition to dealing with physical and psychological burdens, patients with MS also experience a higher prevalence of comorbid conditions. Results from a recent study demonstrated that approximately 62% of patients with MS had comorbidities; the most common conditions included depression (24%), anxiety (23%), hypertension (13%), migraine (12%), smoking or history of smoking (10%) and obesity (9%). (9) Comorbidities may affect MS severity and outcomes, which implicates the importance of screening and monitoring for comorbidities.
Economic impact — MS has the second-highest all-cause medical costs associated with chronic conditions (after congestive heart failure), with total all-cause per-patient healthcare costs — direct and indirect — of up to $54,244 annually. (10) As the disease progresses and disability increases, costs also escalate. For a patient with severe disability, average annual healthcare costs can reach $100,000 or more. (11) Direct costs associated with MS, comprising, on average, 77% of costs, can be primarily attributed to prescription medications, (10) which are taken by 57.5% of people with MS in the United States. (12) Although high, the cost of medications may be offset by medication efficacy in preventing relapse and disability. (4,13) Use of certain therapies may also relate to improved rates of employment among patients with MS, according to a study conducted in Australia. (14) Unemployment related to MS disability is higher than for any other reason, and loss of productivity contributes to up to 44% of MS costs in the United States and Europe. (15) According to results from a case report form questionnaire, 38.5% of 437 patients with MS were underemployed or unemployed because of MS. The most common reason was fatigue. (16)