The cost of delaying treatment in multiple sclerosis: what is lost is not regained

Benefits of early treatment with natalizumab: a real-world study

BACKGROUND

The impact of early versus later high-efficacy disease-modifying therapy (DMT) in patients with multiple sclerosis (MS) is uncertain. This study reported the association of early versus later natalizumab treatment with real-world clinical outcomes in MS patients.

METHODS

The study included 661 participants diagnosed with MS in 1994 or later from 7 US centers participating in the MS Partners Advancing Technology for Health Solutions (MS PATHS) network. Time to natalizumab treatment between diagnosis and first infusion (TTNT) was determined from the Tysabri Outreach: Unified Commitment to Health (TOUCH) registry. Clinical outcomes were defined using neuroperformance tests included in the Multiple Sclerosis Performance Test. Associations were tested using TTNT as a categorical and continuous variable. Linear mixed models addressed within-subject and within-site clustering.

RESULTS

TTNT varied from 0.1 to 19.8 years (median [interquartile range] 4.2 [1.8, 9.0] years). A significant association between later natalizumab use and worse outcomes was demonstrated for walking speed (p < 0.001), processing speed (p < 0.001), manual dexterity (p < 0.001), brain atrophy (p = 0.001), and T2 lesion volume (p = 0.02). Covariate-adjusted modelling of a sensitivity population diagnosed with MS in 2006 or later (n = 424) demonstrated significant associations between longer TTNT and worse walking speed (p < 0.05), processing speed (p < 0.001), and manual dexterity (p < 0.001).

CONCLUSION

Later initiation of natalizumab was associated with worse clinical and radiologic imaging outcomes. Thus, high-efficacy DMT may have greater benefit when started earlier in MS patients. These results provide a rationale for randomized controlled trials to further assess the impact of early highly-effective DMT use versus later escalation of therapy.

Alemtuzumab Use in Clinical Practice: Recommendations from European Multiple Sclerosis Experts

Alemtuzumab (Lemtrada™) is a humanized monoclonal antibody approved in more than 50 countries. Within the European Union, alemtuzumab is indicated for the treatment of adult patients with relapsing-remitting multiple sclerosis (RRMS) with active disease defined by clinical or imaging features; in the USA, the indication states that alemtuzumab should generally be reserved for the treatment of patients with relapsing forms of multiple sclerosis who have had an inadequate response to two or more disease-modifying therapies (DMTs). In clinical trials, alemtuzumab demonstrated efficacy in treatment-naïve patients with active RRMS and those relapsing on prior DMTs, with a consistent and manageable safety and tolerability profile. The European Union indication provides physicians with significant flexibility regarding treatment decisions, affording the opportunity for individualized treatment. Thus, alemtuzumab may be an appropriate treatment choice across a broad range of patients with RRMS, including, for example, treatment-naïve patients with active disease, patients with highly active disease, or for patients relapsing on prior DMTs. There are several practicalities to consider when using alemtuzumab, including the unique dosing regimen, administered via intravenous infusion on 5 consecutive days at baseline and on 3 consecutive days 12 months later, and as-needed retreatment (3 consecutive days at least 12 months after the last course) in cases of disease recurrence. Additionally, routine monthly monitoring is required for up to 48 months after the last infusion to promptly identify potentially serious autoimmune adverse events. Given these considerations, it is beneficial to gain insight into how alemtuzumab is being used in the real-world clinical setting. Here, we report recommendations from European multiple sclerosis experts regarding best practices for alemtuzumab treatment, including management of adverse events and compliance with ongoing safety monitoring requirements.

Estimating long-term effects of disease-modifying drug therapy in multiple sclerosis patients

Two methods were used to estimate the long-term impact of disease-modifying drug therapy (DMDT) in patients with relapsing multiple sclerosis (MS) who completed a placebo-controlled, randomized clinical trial of interferon beta-1a (IFNβ-1a). The study cohort consisted of patients with ambulatory relapsing MS who had previously participated in a placebo-controlled clinical trial for two years. At its end, patients were managed in an unstructured fashion by their neurologists and re-evaluated at an average of 6.1 years after the end of the trial. Follow-up evaluation was obtained for 93% of the 172 eligible patients. Because study inclusion criteria required that all patients have an Expanded Disability Status Scale (EDSS) score of ≤3.5 at entry, disability progression at follow-up was defined as EDSS≥6.0. Two methods were used to estimate the expected proportions that reached EDSS≥6.0 at follow-up. Estimates were compared with observed proportions. Method 1 used progression rates observed during the two-year phase III clinical trial and the percentage of time that patients were on DMDT during the follow-up period. Method 2 used progression rates from a natural history comparison group of relapsing-remitting MS patients. At the eight-year follow-up, 42.0% of the original placebo patients and 29.1% of the original IFNβ-1a patients reached an EDSS ≥ 6.0, an observed treatment effect of approximately 30%. Using method 1, it was estimated that 36.3% of the original placebo patients and 27.6% of the original IFNβ-1a patients should have reached an EDSS ≥ 6.0. Use of the natural history control group (method 2) predicted less plausible outcomes. Estimated proportions of patients reaching the endpoint were 63.3% for the original placebo group and 55.8% for the original IFNβ-1a group. Treatment effect sizes of 75-90% would be required to match estimates from method 2 with the observed outcome. The paucity of data on the long-term treatment of patients with MS may be aided by applying these or similar methods to vigorously followed cohorts of patients.

Disease-modifying agents in multiple sclerosis

Over the past two decades, major advances have been made in the development of disease-modifying agents (DMAs) for multiple sclerosis (MS), and nine agents are now licensed for use in the treatment of MS in the United States. Clinical trials have demonstrated that a number of investigational agents have beneficial effects on clinical and radiographic measures of disease activity, thus the repertoire of available DMAs in MS will likely continue to expand moving forward. Although many of the first-line DMAs have the benefits of established long-term safety and tolerability, in some patients, treatment with one of the more potent novel agents may be appropriate. However, the use of novel agents must be approached with caution, since short-term clinical trials give little information on the long-term efficacy and safety of novel DMAs in MS patients. This chapter will consider the efficacy and safety of both established and investigational agents for the treatment of MS.

Multiple sclerosis in the Arabian Gulf countries: a consensus statement

The epidemiology of multiple sclerosis (MS) is rapidly changing in many parts of the world. Based on the Kurtzke classification, the Arabian Gulf Region is located in a low-risk zone for MS; however, recent studies suggest a moderate-to-high prevalence nearby (31-55 MS per 10,0000 individuals), with an increase in incidence in recent years. The relapsing-remitting disease course ratio is 2.5:1 versus the primary progressive type. In a geographic area that was previously associated with low prevalence; the recent high prevalence and fast rising incidence of MS in the gulf countries, encouraged the neurologists of this region to meet in a consensus panel, in order to share our latest findings in terms of MS epidemiology and consent on MS management in the Arabian Gulf. Therefore 20 key opinion leader neurologists and MS experts representing various countries of the Arabian Gulf have met in Dubai on the 2 and 3 February 2012, they shared their latest epidemiological findings, discussed recent MS aspects in the region, and consented on MS management relevantly to this geographic area.

Multiple sclerosis in the Levant: a regional consensus statement

The epidemiology of multiple sclerosis (MS) is rapidly changing in many parts of the world. In a geographic area that was previously associated with low prevalence, recent studies showing high prevalence and fast rising incidence of MS in the Levant countries led us neurologists of this region to meet in a consensus panel, in order to share our latest findings in terms of MS epidemiology and consent on MS management in the Levant. Twelve neurologists and MS experts representing various countries of the Levant (Lebanon, Syria, Jordan and Iraq) have met in Beirut on the 17(th) of February 2013, shared their latest epidemiological findings, discussed recent MS aspects in the region, and drafted a consensus on MS management relevant to this geographic area.

Multiple Sclerosis Severity Scale and whole-brain N-acetylaspartate concentration for patients' assessment

BACKGROUND

The ability to predict the course of multiple sclerosis (MS) is highly desirable but lacking.

OBJECTIVE

To test whether the MS Severity Scale (MSSS) and global neuronal viability, assessed through the quantification of the whole-brain N-acetylaspartate concentration (WBNAA), concur or complement the assessment of individual patients' disease course.

METHODS

The MSSS and average WBNAA loss rate (ΔWBNAA, extrapolated based on one current measurement and the assumption that at disease onset neural sparing was similar to healthy controls, obtained with proton magnetic resonance (MR) spectroscopy and magnetic resonance imaging (MRI)) from 61 patients with MS (18 male and 43 female) with long disease duration (15 years or more) were retrospectively examined. Some 27 patients exhibited a 'benign' disease course, characterized by an Expanded Disability Status Scale score (EDSS) of 3.0 or less, and 34 were 'non-benign': EDSS score higher than 3.0.

RESULTS

The two cohorts were indistinguishable in age and disease duration. Benign patients' EDSS and MSSS (2.1 ± 0.7, 1.15 ± 0.60) were significantly lower than non-benign (4.6 ± 1.0, 3.6 ± 1.2; both p < 10(-4)). Their respective average ΔWBNAA, 0.10 ± 0.16 and 0.11 ± 0.12 mM/year, however, were not significantly different (p > 0.7). While MSSS is both sensitive to (92.6%) and specific for (97.0%) benign MS, ΔWBNAA is only sensitive (92.6%) but not specific (2.9%).

CONCLUSION

Since the WBNAA loss rate is similar in both phenotypes, the only difference between them is their clinical classification, characterized by MSSS and EDSS. This may indicate that 'benign' MS probably reflects fortuitous sparing of clinically eloquent brain regions and better utilization of brain plasticity.

Evolving expectations around early management of multiple sclerosis

Multiple sclerosis is a progressive inflammatory disease of the central nervous system. With prevention or at least delay of disease progression as a key target in the management of multiple sclerosis, current opinion on treatment encourages early intervention with well-tolerated disease-modifying treatments in order to optimize long-term clinical outcomes. Patients presenting with a clinically isolated syndrome (CIS) may progress to clinically definite multiple sclerosis, and clinical trials have demonstrated that early treatment with interferon beta can reduce the conversion rate. Cognitive impairment may already be present in patients with CISs. Today there is evolving evidence that cognitive impairment may be relevant for prognosis and that early treatment with interferon beta may also have a protective effect on the cognitive function. As an accumulation of neuronal loss is now considered to underlie the development of persistent disability in multiple sclerosis, it is crucial that treatment can protect against neuronal damage. In addition to its anti-inflammatory activity, interferon beta may have direct and indirect neuroprotective effects, and several studies have explored the role of interferon beta in regulating neuroprotective factors. With over 15 years of clinical experience as evidence, the long-term safety and efficacy of interferon beta treatment is unquestionable. Results from the CIS studies have demonstrated the high percentage of patients converting to clinically definite multiple sclerosis without treatment and the short- and long-term benefits of an early use of disease-modifying treatments. These findings support starting disease-modifying treatment as soon as the diagnosis of MS is reasonably formulated.

Cost sharing, benefit design, and adherence: the case of multiple sclerosis

PURPOSE

The authors focus on understanding the relationship between costs and cost sharing on medication adherence for individuals who initiated a disease-modifying therapy (DMT) for the treatment of multiple sclerosis (MS). DMTs reduce the risk of relapse and are an essential component of MS treatment. Furthermore, the authors compare monthly payment levels for copayments versus coinsurance and estimate the effects on adherence.

METHODS

Using the MarketScan Commercial Claims and Encounters database evidence from July 1 2005 to March 31 2008, the authors employ a multivariate two-stage least-squares model (2SLS) to examine the impact of copayments or coinsurance on the medication possession ratio (MPR).

FINDINGS

Descriptive results show that the mean out-of-pocket (OOP) costs of DMT per month were higher for patients with coinsurance than for patients with copayments. For the cohort of patients with copayment there was little difference in monthly copayments across adherence thresholds. Regression analysis shows that an increase in cost sharing reduces adherence overall, but this effect was small and insignificant in the copayment cohort. In contrast, in the coinsurance cohort increased cost sharing was significantly associated with decreased adherence to DMT medication; with a 10% increase in cost sharing leading to an 8.6% decline in adherence.

IMPLICATIONS

Employers increasingly rely on coinsurance, despite evidence that reliance on coinsurance results in lower adherence. Our research findings suggest that coinsurance appears to be a greater obstacle to compliance, confirming predictions found in the theoretical literature.

ORIGINALITY

This research converted counts of injectable treatments into a continuous adherence measure. Previous literature on cost sharing did not examine MS.

Treatment of multiple sclerosis: role of natalizumab

The results on relapse rate and disease progression of available drugs for multiple sclerosis are shown, as well as their most relevant side effects. Results from pivotal and long-term follow-up studies support the efficacy and safety of interferons and glatiramer acetate. The treatment with mitoxantrone is limited by the occurrence of infertility, cardiotoxicy and leukaemia. Efficacy and tolerability of natalizumab are undisputable, compared to other drugs. Risks related to its treatment are PML, opportunistic infections, hepatotoxicity, melanoma, and their occurrence needs to be more exactly assessed by post-marketing surveillance. The principles of induction versus escalating therapy are also discussed. The final therapeutic decision is based on the evaluation of the disease state and prognosis, based on clinical and instrumental measures, and on the safety/efficacy profile of each treatment.

Real-life impact of early interferon beta therapy in relapsing multiple sclerosis

OBJECTIVE

Recent findings support greater efficacy of early vs. delayed interferon beta (IFNbeta) treatment in patients with a first clinical event suggestive of multiple sclerosis (MS). We aimed to evaluate the effectiveness of early IFNbeta treatment in definite relapsing-remitting MS (RRMS) and to assess the optimal time to initiate IFNbeta treatment with regard to the greatest benefits on disability progression.

METHODS

A cohort of 2,570 IFNbeta-treated RRMS patients was prospectively followed for up to 7 years in 15 Italian MS Centers. A Cox proportional hazards regression model adjusted for propensity score (PS) quintiles was used to assess differences between groups of patients with early vs. delayed IFNbeta treatment on risk of reaching a 1-point progression in the Expanded Disability Status Scale (EDSS) score, and the EDSS 4.0 and 6.0 milestones. A set of PS-adjusted Cox hazards regression models were calculated according to different times of treatment initiation (within 1 year up to within 5 years from disease onset). A sensitivity analysis was performed to assess the robustness of findings.

RESULTS

The lowest hazard ratios (HRs) for the three PS quintiles-adjusted models were obtained by a cutoff of treatment initiation within 1 year from disease onset. Early treatment significantly reduced the risk of reaching a 1-point progression in EDSS score (HR = 0.63; 95% CI = 0.48-0.85; p < 0.002), and the EDSS 4.0 milestone (HR = 0.56; 95% CI = 0.36-0.90; p = 0.015). Sensitivity analysis showed the bound of significance for unmeasured confounders.

INTERPRETATION

Greater benefits on disability progression may be obtained by an early IFNbeta treatment in RRMS.

High-dose, high-frequency recombinant interferon beta-1a in the treatment of multiple sclerosis

BACKGROUND

There is at present no cure for multiple sclerosis (MS), and existing therapies are designed primarily to prevent lesion formation, decrease the rate and severity of relapses and delay the resulting disability by reducing levels of inflammation.

OBJECTIVE

The aim of this review was to assess the treatment of relapsing MS with particular focus on subcutaneous (s.c.) interferon (IFN) beta-1a.

METHOD

The literature on IFN beta-1a therapy of MS was reviewed based on a PubMed search (English-language publications from 1990) including its pharmacodynamics and pharmacokinetics, clinical efficacy in relapsing MS as shown in placebo-controlled studies and in comparative trials, efficacy in secondary progressive MS, safety and tolerability, and the impact of neutralizing antibodies.

CONCLUSION

The literature suggests that high-dose, high-frequency s.c. IFN beta-1a offers an effective option for treating patients with relapsing MS, with proven long-term safety and tolerability, and has a favourable benefit-to-risk ratio compared with other forms of IFN beta.

Interferon-beta treatment for multiple sclerosis

Multiple sclerosis (MS) is the leading nontraumatic cause of neurologic disability in young adults. Interferon-beta, approved for use in 1993, was the first treatment to modify the course and prognosis of the disease and remains a mainstay of MS treatment. Numerous large-scale clinical trials in early, active patient populations have established the clinical efficacy of interferon-beta in reducing relapses and delaying disability progression. Although its mechanism of action remains incompletely understood, a reduction in active lesions seen on magnetic resonance imaging implies primary anti-inflammatory properties, a mechanism supported by basic immunologic research. Variation in individual patient responsiveness to interferon-beta may be due to disease variability or differential induction of interferon-stimulated genes. The magnitude of the therapeutic effect appears to be similar among products, but the optimal dose, route, and frequency of administration of the drug remain uncertain.

New natural history of interferon-beta-treated relapsing multiple sclerosis

OBJECTIVE

To investigate the impact of interferon-beta (IFNbeta) on disease progression in relapsing-remitting multiple sclerosis patients.

METHODS

A cohort of 1,504 relapsing-remitting multiple sclerosis (1,103 IFNbeta-treated and 401 untreated) patients was followed for up to 7 years. Cox proportional hazards regression adjusted for propensity score inverse weighting was used to assess the differences between the two groups for three different clinical end points: secondary progression (SP) and irreversible Expanded Disability Status Scale (EDSS) scores 4 and 6. Times from first visit and from date of birth were used as survival time variables.

RESULTS

The IFNbeta-treated group showed a highly significant reduction in the incidence of SP (hazard ratio [HR], 0.38, 95% confidence interval [CI], 0.24-0.58 for time from 1st visit; HR, 0.36, 95% CI, 0.23-0.56 for time from date of birth; p < 0.0001), EDSS score of 4 (HR, 0.70, 95% CI, 0.53-0.94 for time from first visit; HR, 0.69, 95% CI, 0.52-0.93 for time from date of birth; p < 0.02), and EDSS score of 6 (HR, 0.60, 95% CI, 0.38-0.95 for time from first visit; HR, 0.54, 95% CI, 0.34-0.86 for time from date of birth; p < or = 0.03) when compared with untreated patients. SP and EDSS scores of 4 and 6 were reached with significant delays estimated by times from first visit (3.8, 1.7, and 2.2 years) and from date of birth (8.7, 4.6, and 11.7 years) in favor of treated patients. Sensitivity analysis confirmed findings.

INTERPRETATION

IFN-beta slows progression in relapsing-remitting multiple sclerosis patients.

Natalizumab update

PURPOSE

The pharmacology, pharmacokinetics, indications, clinical efficacy, adverse effects, drug interactions, and dosage and administration of natalizumab are reviewed.

SUMMARY

Natalizumab, the first commercially available selective adhesion-molecule inhibitor, is approved as monotherapy for the treatment of patients with relapsing forms of multiple sclerosis (MS). Natalizumab exerts its immunologic effects by targeting the alpha4 integrin receptor, the site responsible for the migration of leukocytes from the blood into inflamed tissues. Because of the increased risk of progressive multifocal leukoencephalopathy (PML), natalizumab is generally recommended for patients who have had an inadequate response to or are intolerant of alternative MS therapies. Data evaluating the efficacy and safety of natalizumab for the treatment of MS are available from published Phase II and III trials. The most common adverse effects reported include headache, fatigue, urinary-tract infection, depression, arthralgia, and lower respiratory-tract infection. The recommended dosage of natalizumab for the treatment of relapsing forms of MS is 300 mg administered by i.v. infusion over one hour once every four weeks. Natalizumab is available only through a risk-minimization program run by the manufacturer.

CONCLUSION

Natalizumab offers an effective treatment option for patients with MS who have had an inadequate response to or are intolerant of alternative MS therapies. Because of its potential to increase the risk of PML, the risks and benefits should be carefully weighed before initiating natalizumab therapy in patients with MS. Natalizumab should not be used to treat Crohn's disease or any other unapproved indication until more postmarketing safety data are available.

Prospective assessment of changing from placebo to IFN beta-1a in relapsing MS: The PRISMS study

The efficacy of interferon (IFN) beta has been shown in several placebo-controlled, parallel-group studies in relapsing-remitting multiple sclerosis (RRMS). PRISMS, the largest such study to date, clearly demonstrated the efficacy of IFN beta-1a on all outcome measures over 2 years during the placebo-controlled, parallel-group phase. However, this study's placebo-crossover design also provided us with a unique opportunity to conduct a prospective within-group assessment, eliminating the impact of inter-patient variability. At the start of year 3, patients receiving placebo during years 1-2 were re-randomized in a dose-blinded fashion to receive IFN beta-1a, 22 or 44 mcg subcutaneously three times weekly, during years 3 and 4. Clinic visits occurred 3-6 monthly and T2 MRI scans were obtained after 1 and 2 years on therapy. Comparison of the mean relapse count per patient over 2 years (the primary outcome measure) during time on placebo (years 1 and 2) with that during active treatment (years 3 and 4) revealed a decrease from 2.6 to 1.2 in both dose groups (54% relative reduction; p<0.001). Disability progression, T2 MRI lesion activity and accumulation of T2 lesion burden were also significantly improved with therapy (p<0.01). No new safety issues were noted. These data provide further support for IFN beta-1a's efficacy in RRMS. The ability to detect significant treatment effects with reduced patient numbers in this type of before/after analysis, may be due to the reduction in inter-patient variability.

Benefits of high-dose, high-frequency interferon beta-1a in relapsing-remitting multiple sclerosis are sustained to 16 months: final comparative results of the EVIDENCE trial

The EVIDENCE trial demonstrated that interferon (IFN) beta-1a, 44 mcg subcutaneously (sc) three times weekly (tiw) (Rebif), was significantly more effective than IFN beta-1a, 30 mcg intramuscularly (im) once weekly (qw) (Avonex), in reducing relapses and magnetic resonance imaging (MRI) activity in patients with relapsing-remitting multiple sclerosis at both 24 and 48 weeks of therapy. We now present final comparative data on these patients, showing that the superior efficacy of IFN beta-1a, 44mcg sc tiw, for relapse measures and MRI activity, compared with IFN beta-1a, 30mcg im qw, was sustained for at least 16 months. The development of antibodies to IFN was associated with reduced efficacy on MRI measures and fewer IFN-related adverse events, but did not have an impact on relapse outcomes.

Improving MS patient care

Multiple sclerosis (MS) is a multidimensional, chronic, neurological disease affecting young people that often interferes with their life and career plans. Patient care begins at the time of diagnosis, and particular emphasis should be placed on proper education about the variable disease course and treatment options. Clinical assessment at regular intervals using quantitative measures is recommended in order to obtain important information on the effects of disease-modifying and/or symptomatic treatment. In addition to optimising therapy, it is imperative to develop effective and properly resourced care services for MS patients that will address their complex and lifelong requirements.

Interferon-β in the treatment of relapsing–remitting multiple sclerosis

The role of interferon-beta as a disease-modifying drug (DMD) for the treatment of relapsing-remitting multiple sclerosis (RRMS) is now well established, and its efficacy has been demonstrated unequivocally in large-scale clinical trials. However, current evidence suggests that in order to increase the benefit of therapy, use of an effective drug and dosing regimen should be commenced early in the course of the disease, a finding that places new emphasis on the need for early diagnosis. Indeed, it is now known that MS lesions often develop at a subclinical level and that axonal damage occurs even in the very early stages of the disease. Moreover, such damage may be irreversible, and there is strong evidence to suggest that efficacy lost as a consequence of delay in the onset of treatment or the use of a suboptimal drug regimen cannot be regained. At present, the choice of interferon-beta is complicated by the availability of 3 different products, each with a different dosing regimen. Although the optimal interferon-beta dosing regimen for RRMS has been the focus of much discussion, the issues of dose, and particularly dosing frequency, have not been satisfactorily addressed in clinical trials until recently. Over the last 2 years, however, 3 comparative studies of interferon-beta products have been conducted. The results obtained from these recent trials underline the importance of both dose and dosing frequency and indicate that for improved efficacy in RRMS, interferon-beta therapy should be administered frequently at the highest tolerable, and thus most effective, dose.

Cognitive impairment in probable multiple sclerosis

OBJECTIVES

To evaluate and characterise cognitive impairment in the very early stage of multiple sclerosis (MS), in which patients are still diagnosed as suffering from probable MS.

METHODS

The Brief Repeatable Battery-Neuropsychological (BRB-N) that has been validated for MS patients was used. Abnormal performance was defined as one standard deviation below the mean reported for healthy age matched subjects. Neurological disability and brain magnetic resonance imaging (MRI) were performed for all patients. Correlation coefficients were calculated between disease burden variables and performance on the BRB-N.

RESULTS

Sixty seven patients with probable MS were evaluated within a mean of one month of the onset of new neurological symptoms. Evidence for the presence of cognitive impairment was shown in 53.7% of patients. Verbal abilities and attention span were most frequently affected. Impairment was not correlated with neurological disability or MRI disease burden.

CONCLUSION

Prevalent cognitive impairment already exists at onset of MS.

Relapsing-remitting multiple sclerosis and whole-brain N-acetylaspartate measurement: evidence for different clinical cohorts initial observations

PURPOSE

To quantify the rate of concentration decline of neuronal marker N-acetylaspartate (NAA) in the entire brain of patients with relapsing-remitting multiple sclerosis (MS) in relation to healthy age-matched control subjects.

MATERIALS AND METHODS

Whole-brain NAA (WBNAA) concentration was quantified in 49 patients with relapsing-remitting MS by using magnetic resonance (MR) imaging and proton MR spectroscopy. It was statistically analyzed by using Spearman rank correlation coefficients to test the intragroup relationship between WBNAA and Expanded Disability Status Scale (EDSS) score and Mann-Whitney analyses to test for differences between subgroups' EDSS scores versus previously published WBNAA values for healthy subjects, disease duration, and age.

RESULTS

Analyses indicated three subgroups of WBNAA dynamics: Ten patients' conditions were "stable," exhibiting an insignificant change of about 0% (0.02/14.37) per year of clinically definite disease duration (P =.54); 27 patients showed "moderate" decline, -2.8% (-0.34/12.18) per year (P <.01); and 12 patients experienced "rapid" decline, -27.9% (-3.39/12.14) per year (P <.01). No correlation was found between WBNAA deficit, EDSS score, and age.

CONCLUSION

Ascertaining an individual's NAA concentration dynamics might enable early forecast of disease course, reflect disease severity and thus influence treatment decisions, and improve clinical trial efficiency by allowing selection of candidates on the basis of WBNAA dynamics in addition to clinical status.