Using instrumental variables to correct for bias in real-world cohort studies of the effects of disease-modifying treatment in MS

BACKGROUND

Estimating the effect of disease-modifying treatment of MS in observational studies is impaired by bias from unmeasured confounders, in particular indication bias.

OBJECTIVE

To show how instrumental variables (IVs) reduce bias.

METHODS

All patients with relapsing onset of MS 1996-2010, identified by the nationwide Danish Multiple Sclerosis Registry, were followed from onset. Exposure was treatment index throughout the first 12 years from onset, defined as a cumulative function of months without and with medium- or high-efficacy treatment, and outcomes were hazard ratios (HRs) per unit treatment index for sustained Expanded Disability Scale Score (EDSS) 4 and 6 adjusted for age at onset and sex, without and with an IV. We used the onset cohort (1996-2000; 2001-2005; 2006-2010) as an IV because treatment index increased across the cohorts.

RESULTS

We included 6014 patients. With conventional Cox regression, HRs for EDSS 4 and 6 were 1.15 [95% CI: 1.13-1.18] and 1.17 [1.13-1.20] per unit treatment index. Only with IVs, we confirmed a beneficial effect of treatment with HRs of 0.86 [0.81-0.91] and 0.82 [0.74-0.90].

CONCLUSION

The use of IVs eliminates indication bias and confirms that treatment is effective in delaying disability. IVs could, under some circumstances, be an alternative to marginal structural models.

Effectiveness of first generation disease-modifying therapy to prevent conversion to secondary progressive multiple sclerosis

BACKGROUND

The use of disease-modifying therapies (DMTs) in multiple sclerosis (MS) has been associated with reduced relapse rates and accumulation of disability. However, studies examining impact of DMT on risk of transition to secondary progressive MS (SPMS) leveraging population-based nationwide data are still rare. Here, we determine the population incidence of conversion to SPMS using two consecutive nation-wide cohorts, one immediately before and one after the introduction of DMT in Sweden.

METHODS

We included two consecutive population cohorts of relapsing-remitting MS (RRMS) from the Swedish national MS register for the periods 1975-1994 (n = 2161), before DMT availability, and 1995-2011 (n = 3510), in which DMTs, mainly first generation DMT (injectables), became available and eventually were used by 70% of patients. We explored the risk of transition to SPMS as a calendar year function encompassing the two cohorts. In addition, we determined the incidence of transition to SPMS through age strata below and above 50 years in untreated and treated patient subgroups.

RESULTS

The risk of conversion to SPMS (adjusted for current age, current time since onset, calendar year and sex) was significantly lower in the second compared with the first population cohort (hazard ratio 0.58; CI 0.48, 0.70). The risk of SPMS conversion per calendar year decreased by 2.6% annually (p < 0.001) after 1995. The risk of SPMS conversion increased with age until age 50. Thereafter, it was unchanged or decreased among those with early MS onset age (<35 years), but continued to increase with onset at higher age, with similar trends in treated and untreated subgroups.

CONCLUSION

The incidence of SPMS conversion significantly decreased at the population level after introduction of first generation DMTs by 1995. DMT efficiency was confirmed by a downward turn of the annual trajectory of the risk of SPMS conversion after 1995. An onset age determined pattern of variable SPMS incidence in higher age appeared in both treated and untreated strata. While first generation DMT delayed conversion to SPMS, their long-term effect was only moderate.

Apparent changes in the epidemiology and severity of multiple sclerosis

Multiple sclerosis (MS) is an immunological disease that causes acute inflammatory lesions and chronic inflammation in the CNS, leading to tissue damage and disability. As awareness of MS has increased and options for therapy have come into use, a large amount of epidemiological data have been collected, enabling studies of changes in incidence and disease course over time. Overall, these data seem to indicate that the incidence of MS has increased, but the course of the disease has become milder, particularly in the 25 years since the first disease-modifying therapies (DMTs) became available. A clear understanding of these trends and the reasons for them is important for understanding the factors that influence the development and progression of MS, and for clinical management with respect to prevention and treatment decisions. In this Review, we consider the evidence for changes in the epidemiology of MS, focusing on trends in the incidence of the disease over time and trends in the disease severity. In addition, we discuss the factors influencing these trends, including refinement of diagnostic criteria and improvements in health-care systems that have increased diagnosis in people with mild disease, and the introduction and improvement of DMT.

A non-parametric propensity score for estimating the effect of interferon-beta or glatiramer acetate on long-term outcomes of multiple sclerosis

BACKGROUND

The few observational studies that investigated the long-term effects of interferon-beta and glatiramer acetate were usually focused on progression to irreversible disability and other outcomes such as number of relapses and transition to secondary-progressive multiple sclerosis (SPMS) have been rarely studied. The objective of this paper is to estimate the effect of interferon-beta/glatiramer acetate on progression to irreversible disability, transition from relapsing-remitting multiple sclerosis (RRMS) to SPMS and the rate of relapses over 10 years.

METHODS

Analyses included 2498 patients with confirmed diagnosis of RRMS followed in Montréal from 1977 to 2016. Marginal structural models with propensity score for treatment and censoring were used to account for potential confounding and attrition. Specifically, we used pooled logistic regression for progression to irreversible disability and transition to SPMS, and Poisson models for the rate of relapses.

RESULTS

77% of subjects were female and the median age at RRMS diagnosis was 35 years. The hazard of progression to irreversible disability was lower among treated patients than untreated patients (HR=0.73, 95% CI [0.57-0.94]). We did not find evidence of an association between interferon-beta/glatiramer acetate and the rate of transition to SPMS either over the 3-month intervals or for the duration of treatment. Patients treated for >5 years had a lower rate of relapses compared to those untreated (HR=0.70, 95% CI [0.57-0.86]).

CONCLUSION

Treatment with interferon-beta/glatiramer acetate suggests a beneficial effect on progression to irreversible disability and rate of relapses, but not on transition to SPMS.

Cumulative effects of therapies on disability in relapsing multiple sclerosis

Background:

Long-term effectiveness of treatment remains a key question in multiple sclerosis (MS) and the cumulative effects of past treatment have not been investigated so far.

Objective:

Explore the relationship between treatment exposure and disability risk in patients with relapsing-remitting multiple sclerosis (RRMS).

Methods:

A total of 2285 adult patients from the French nationwide cohort were included. Outcomes were irreversible EDSS4, and conversion to secondary progression of multiple sclerosis (SPMS). Associations between treatments and risk of disability were assessed using a novel weighted cumulative exposure model, assuming a 3-year lag to account for reverse causality. This flexible approach accounts for past exposure in a multivariate Cox proportional hazards model by computing a weight function.

Results:

At baseline, mean ± standard deviation age of patients was 33.4 ± 8.9 years and 75.0% were women. A 15-year continuous treatment starting 20 years ago was associated with a decrease in risk of 26% for irreversible EDSS4, and 34% for SPMS compared to a 5-year treatment starting 10 years ago. The risk of disability decreased with increasing duration of exposure to disease-modifying treatment (DMT).

Conclusion:

Long-term use of treatments in RRMS has a stronger beneficial cumulative impact than only early uses and delays the occurrence of moderate disability and conversion to SPMS.

Pediatric Multiple Sclerosis Severity Score in a large US cohort

OBJECTIVE

To characterize disease severity and distribution of disability in pediatric-onset multiple sclerosis (POMS) and to develop an optimized modeling scale for measuring disability, we performed a multicenter retrospective analysis of disability scores in 873 persons with POMS over time and compared this to previously published data in adults with multiple sclerosis (MS).

METHODS

This was a retrospective analysis of prospectively collected data collected from 12 centers of the US Network of Pediatric MS Centers. Patients were stratified by the number of years from first symptoms of MS to Expanded Disability Status Scale (EDSS) assessment and an MS severity score (Pediatric Multiple Sclerosis Severity Score [Ped-MSSS]) was calculated per criteria developed by Roxburgh et al. in 2005.

RESULTS

In total, 873 patients were evaluated. In our cohort, 52%, 19.4%, and 1.5% of all patients at any time point reached an EDSS of 2.0, 3.0, and 6.0. Comparison of our Ped-MSSS scores and previously published adult Multiple Sclerosis Severity Scores (MSSS) showed slower progression of Ped-MSSS with increasing gaps between higher EDSS score and years after diagnosis. Decile scores in our POMS cohort for EDSS of 2.0, 3.0, and 6.0 were 8.00/9.46/9.94, 7.86/9.39/9.91, and 7.32/9.01/9.86 at 2, 5, and 10 years, respectively. Notable predictors of disease progression in both EDSS and Ped-MSSS models were ever having a motor relapse and EDSS at year 1. Symbol Digit Modalities Test (SDMT) scores were inversely correlated with duration of disease activity and cerebral functional score.

CONCLUSIONS

Persons with POMS exhibit lower EDSS scores compared to persons with adult-onset MS. Use of a Ped-MSSS model may provide an alternative to EDSS scoring in clinical assessment of disease severity and disability accrual.

Do disease-modifying drugs (DMD) have a positive impact on the occurrence of secondary progressive multiple sclerosis? Yes

During the 20 past years, the management of multiple sclerosis (MS) has largely changed especially concerning therapeutical approach. Before 1996, treatments were restricted to corticosteroids for relapses, several symptomatic treatments and unselective immunosuppressive drugs (azathioprine, cyclophosphamide, methotrexate) with a low evidence of any efficacy. In the present review, we analyze the principal real-life cohorts of MS during several periods (before therapeutical modern area, first-generation treatment area and most recent period). Despite many methodological problems, we observe globally a delay of around 3-5 years between untreated cohorts and first-generation treatments for going to EDSS 6 which is probably the most robust score. This delay is clearly increase to at least 15 years with the most recent cohort treated first and second-line treatments confirming that early and more intensive treatment are necessary to have a long-term efficacy on disability progression and especially on severe disability represent by EDSS 6. Larger cohorts with longer follow-up is necessary to confirm these tendencies and OFSEP observatory or MS base will probably provide us the possibility to conclude in a couple of years.

Changes in the Risk of Reaching Multiple Sclerosis Disability Milestones In Recent Decades: A Nationwide Population-Based Cohort Study in Sweden

Importance

Clinicians' experience and findings from recent natural history studies suggest that multiple sclerosis (MS) may now be running a more slowly progressing course than before.

Objective

To investigate whether the risk of reaching MS disability milestones has changed over the last decade in Sweden.

Design, Setting, and Participants

A nationwide population-based retrospective cohort study. By April 2017, 12 512 patients with available information on demographics, MS phenotype, and date of MS onset and diagnosis were registered in the Swedish MS Registry of which 7331 patients with at least 2 recorded Expanded Disability Status Scale scores (EDSS) and diagnosed between January 1995 and December 2010 were included. No further exclusion criteria were applied. Patients were followed up until December 2016 with a median duration follow-up of 8.5 (interquartile range, 4.7-13.8) years. Statistical analysis began in April 2017.

Main Outcomes and Measures

Patients were followed up from MS onset date to the date of sustained EDSS 3.0, 4.0, and 6.0. To handle interval-censored observations, a Weibull model was fit, and the change in the risk of EDSS 3.0, 4.0, and 6.0 over calendar years was estimated and hazard ratios (HRs) with corresponding CIs were calculated.

Results

Of 7331 patients, 5196 (70.9%) were women, and the mean (SD) age at diagnosis was 38.3 (11.7) years. Adjusting for sex, number of clinic visits, diagnostic delay, and onset age, a 3% decrease per calendar year of diagnosis for the risk of sustained EDSS 3.0 (HR, 0.97; 95% CI, 0.96-0.97), a 6% decrease for the risk of EDSS 4.0 (HR, 0.94; 95% CI, 0.93-0.95), and a 7% decrease for the risk of EDSS 6.0 (HR, 0.93; 95% CI, 0.91-0.94) among patients with relapsing-onset MS was found. The trends were not significant for patients with progressive-onset MS (EDSS 3.0: HR, 1.01; 95% CI, 0.98-1.03; EDSS 4.0: HR, 1.00; 95% CI, 0.98-1.02; EDSS 6.0: HR, 1.00; 95% CI, 0.98-1.02).

Conclusions and Relevance

Risk of reaching major disability milestones has significantly decreased over the last decade in patients with relapsing-onset MS in Sweden. Several factors could potentially be responsible for this observation. However, given that no change was seen in disability accrual of patients with progressive-onset MS and the absence of efficacious treatment option in this group, increased use of more efficacious disease-modifying treatments could be a possible driver of this change.

CD4+/CD45RO+: A Potential Biomarker of the Clinical Response to Glatiramer Acetate

Background: Glatiramer acetate (GA) is an effective treatment for the earliest stages of multiple sclerosis (MS)—clinically isolated syndrome (CIS) or clinically definite MS (CDMS). Objective: This study aims to determine the differences in the lymphocyte population (at baseline and the course of five years) between confirmed sustained progression (CSP) and non-CSP groups and to identify potential biomarkers among these parameters that can predict a positive response to the treatment. Methods: Twelve male and 60 female patients were included in the study. Peripheral blood samples were collected before and five years after treatment with GA. The authors compared lymphocyte parameters between the CSP and non-CSP groups by statistical analyses. Univariate and penalized logistic regression models were fitted to identify the best lymphocyte parameters at baseline and their combination for potential biomarkers. Subsequently, the ROC analysis was used to identify cut-offs for selected parameters. Results: The parameter CD4+/CD45RO+ was identified as the best single potential biomarker, demonstrating the ability to identify patients with CSP. Moreover, a combination of four lymphocyte parameters at baseline, relative lymphocyte counts, CD3+/CD69+, CD4+/CD45RO+, and CD4+/CD45RA+ab, was identified as a potential composite biomarker. This combination explains 23% of the variability in CSP, which is better than the best univariate parameter when compared to CD4+/CD45RO+ at baseline. Conclusions: The results suggest that other biomarkers can help monitor the conditions of patients and predict a favourable outcome.

Validation of an algorithm to detect severe MS relapses in administrative health databases

BACKGROUND

Severe relapses that required treatment were important outcomes in the sentinel trials of disease-modifying therapy (DMT). Identifying such relapses in administrative data would allow comparative-effectiveness studies of DMTs to be conducted in real-world clinical settings.

METHODS

All relapsing-remitting (RRMS) and secondary-progressive (SPMS) patients living in Manitoba between 1999 and 2015 were identified using a validated case definition and linkage to the Manitoba MS Clinic database. All healthcare interactions potentially due to relapses were extracted from population-based administrative (hospital, physician claims and prescription) databases. These "relapse markers" included varying thresholds of outpatient prednisone scripts, day hospital or emergency room (ER) codes for intravenous (IV) methylprednisolone therapy, family physician, neurologist or ER physician billing codes and hospital admissions due to MS. Algorithms using combinations of these markers were compared with a reference standard of neurologist-defined relapses. The most useful algorithms were also examined on a biannual basis over the study period to assess for trends in the sensitivity of relapse detection.

RESULTS

1131 participants with RRMS or SPMS were linked to administrative databases. Analysis of potential relapse markers over the whole 1999-2015 time period was limited by inconsistent coding of same day or ER admissions for IV methylprednisolone administration. Widespread adoption of high-dose oral outpatient prednisone for relapses since 2009 resulted in a progressive improvement in relapse marker sensitivity. The best algorithm consisted of oral prednisone prescriptions >50mg/day for 3-60 days and same day hospital or ER assessment codes with MS as the most responsible diagnosis (sensitivity 70%, specificity 100%, PPV 100%, NPV 96%, kappa 0.8 in 2013-2015).

CONCLUSIONS

Severe relapses can be identified from administrative datasets with reasonable accuracy. The trend since 2009 toward outpatient relapse treatment will improve the sensitivity of relapse detection with longitudinal follow-up of this cohort and will allow comparison of severe relapse rates between different DMTs, supporting future comparative effectiveness studies.

Assessing long-term prognosis improvement as a consequence of treatment pattern changes in MS

OBJECTIVE

To assess whether the age at which multiple sclerosis (MS) patients reach Expanded Disability Status Scale (EDSS) milestones changed as long as new drugs for the treatment of MS became available.

METHODS

We evaluated the long-term impact of therapies on disability progression assessing whether there is a detectable delay in the age at which patients reached EDSS milestones in more recent years. We used data collected over more than 30 years in the Center of Brescia, Italy. We compared the age at EDSS = 6 among patients diagnosed with relapsing-remitting MS in different time periods, adjusting for age at diagnosis and median interval among EDSS visits, by a multivariate Cox model.

RESULTS

A total of 1324 MS patients were included. Patients diagnosed in more recent periods reached EDSS = 6 at an older age: the rate at which patients reached EDSS = 6 in those diagnosed in 1991-1995 was similar to those diagnosed in 1980-1990 (hazard ratio ( HR) = 1.09, p = 0.68) and to those diagnosed in 1996-2000 ( HR = 0.85, p = 0.44), it was reduced by 37% in patients diagnosed in 2001-2005 ( HR = 0.63, p = 0.05), by 46% in patients diagnosed in 2006-2010 ( HR = 0.54, p < 0.02).

CONCLUSION

A clear modification of MS course is observed after 2000; among other causes, this can be associated to the changes in the treatment patterns experienced in those years.

Long-term impact of interferon or Glatiramer acetate in multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

In recent years the impact of disease-modifying drugs on long-term progression in multiple sclerosis (MS) was assessed both in observational studies and in extension of randomized controlled trial (RCT). Aim of this work was to quantitatively summarize by a meta-analysis the long-term impact of immunomodulatory drugs (Interferon-Beta (IFN-β) or Glatiramer Acetate (GA)) in relapsing-remitting (RR) MS patients.

METHODS

We collected all published observational studies reporting the long-term efficacy of IFN-β or GA in RRMS patients. The primary outcome was the treatment effect on progression to a sustained EDSS score of 6 or to the Secondary Progressive (SP) phase. A non-parametric approach was adopted to test the overall treatment effect significance, while a random effect model was used to obtain a pooled quantitative estimate of the treatment benefit, in terms of hazard-ratios (HR) or Relative Risks, with their 95% confidence interval (CI).

RESULTS

Fourteen studies, on a total of 13,238 RRMS patients, were included in the meta-analysis. All studies but two reported a consistent effect of immunomodulatory treatment on long-term disease progression; the pooled effect on progression to EDSS 6 or SP was significant (p<0.01) when tested by the non-parametric test. The quantitative estimate of the treatment effect in reducing progression to EDSS 6 in the subset of studies reporting this outcome was HRpooled=0.49 (95% CI: 0.34-0.69), p<0.001.

CONCLUSIONS

Treatment with immunomodulators seems to reduce long-term probability of disability progression. Additional well-designed observational studies could help to confirm these findings.

Estimating typical multiple sclerosis disability progression speed from clinical observations

Introduction

Multiple sclerosis (MS) is a chronic disease of the central nervous system. Estimates of MS natural history (NH) disability progression speed from clinical observations vary worldwide. This may reflect, in part, variance in censoring-bias) (missing observations) and assumptions about when irreversible disability progression events occurred. We test whether estimates of progression speed which assume midpoint survival time at irreversible disability endpoints are significantly faster than estimates which assume maximum survival time, and are more stable across study groups and time periods.

Methods

Our Nova Scotia NH study population includes 2,240 definite relapsing-onset multiple sclerosis (R-MS) natural history patients with 18,078 Expanded Disability Status Scale (EDSS) clinical observations in study period 1979–2010. Progression speed is measured by rate-of-change in range EDSS 0–6 and by survival time at irreversible endpoints EDSS 1–9. Midpoint censoring-bias-reduction methods are applied to clinical observations.

Findings

Typical EDSS increase per year in range EDSS 0–6, assuming midpoint survival time, is estimated to be 0.168 for all R-MS, 0.204 for eventually-DMD-treated patients and 0.155 for never-DMD-treated patients. Estimates assuming midpoint rather than maximum survival time are significantly faster: 16% faster for all R-MS natural history patients, 6% faster for eventually-DMD-treated patients, and 21% faster for never-DMD-treated patients. The variability of estimates across study groups and time periods decreased when midpoint survival time was assumed.

Conclusions

Estimates of typical disease progression speed from 1979–2010 Nova Scotia clinical observations are sensitive to censoring-bias and to analysts’ survival time assumptions. Censoring-bias-adjusted estimates of typical natural history disability progression speed in relapsing-onset multiple sclerosis patients are significantly faster, and less variable within and across study groups and time periods, than unadjusted estimates, and are, arguably, more relevant for various stakeholders. The application of censoring-bias-reduction methods to other multiple sclerosis clinical databases may reduce variability in estimates of disability progression speed worldwide.

Influence of treatments in multiple sclerosis disability: A cohort study

Background and objective:

A critical aspect of multiple sclerosis (MS) treatments is understanding the effect of disease-modifying drugs (DMDs) on the long-term risk of disability and whether the effect is related to disability at start of treatment.

Methods:

We performed an observational study on 3060 MS patients. The effect of therapy on progression to Expanded Disability Status Scale (EDSS) 3.0 and 6.0 from onset was analysed in treated vs untreated (UTP) patients using Cox regression analysis adjusted for propensity score and immortal time bias.

Results:

Compared to UTP, the risks of EDSS 3.0 were 94% and 73% lower in immunomodulant (IMTP-) and immunosuppressant (ISTP-) treated patients, respectively, while the risk of EDSS 6.0 was 86% lower in IMTP. The risk of EDSS 6.0 was, respectively, 91% and 75% lower in 1275 IMTP before and 114 after EDSS 3.0 than in 539 UTP; the risk was higher in IMTP starting therapy after EDSS 3.0 than before (HR = 4.42).

Conclusions:

DMDs delayed long-term disability in MS patients treated either in the early or, to a lesser extent, in the later phase of the disease. Thus, the window of therapeutic opportunity is relatively extended, assuming that early is better than late treatment, but late is better than never.

Time to secondary progression in patients with multiple sclerosis who were treated with first generation immunomodulating drugs

BACKGROUND

It is currently unknown whether early immunomodulatory treatment in relapsing-remitting MS (RRMS) can delay the transition to secondary progression (SP).

OBJECTIVE

To compare the time interval from onset to SP in patients with RRMS between a contemporary cohort, treated with first generation disease modifying drugs (DMDs), and a historical control cohort.

METHODS

We included a cohort of contemporary RRMS patients treated with DMDs, obtained from the Swedish National MS Registry (disease onset between 1995-2004, n = 730) and a historical population-based incidence cohort (onset 1950-64, n = 186). We retrospectively analyzed the difference in time to SP, termed the "period effect" within a 12-year survival analysis, using Kaplan-Meier and Cox regression analysis.

RESULTS

We found that the "period" affected the entire severity spectrum. After adjusting for onset features, which were weaker in the contemporary material, as well as the therapy initiation time, the DMD-treated patients still exhibited a longer time to SP than the controls (hazard ratios: men, 0.32; women, 0.53).

CONCLUSION

Our results showed there was a longer time to SP in the contemporary subjects given DMD. Our analyses suggested that this effect was not solely driven by the inclusion of benign cases, and it was at least partly due to the long-term immunomodulating therapy given.

The path to self-management: a qualitative study involving older people with multiple sclerosis

PURPOSE

This qualitative study sought to explore older people's experience of ageing with multiple sclerosis (MS) and to describe the natural history of self-management from their points of view.

METHODS

Eighteen people over age 55 and living with MS for at least 20 years were recruited from an MS clinic and rehabilitation outpatient records. Interviews (60-80 min), using open-ended questions, explored participants' lifelong experiences of MS. Following interview transcription, data were coded and analyzed; themes, subthemes, and their relationships were described based on consensus.

RESULTS

Participants recounted their diagnosis process, their life experience with MS, and how they eventually accepted their disease, adapted, and moved toward self-management. The findings included vivid descriptions of social relationships, health care interactions, overcoming barriers, and the emotions associated with living with MS. A conceptual model of phases of self-management, from diagnosis to integration of MS into a sense of self, was developed.

CONCLUSIONS

Study participants valued self-management and described its phases, facilitators, and inhibitors from their points of view. Over years and decades, learning from life experiences, trial and error, and interactions with health care professionals, participants seemed to consolidate MS into their sense of self. Self-determination, social support, strong problem-solving abilities, and collaborative relationships with health professionals aided adaptation and coping. Findings from this study make initial steps toward understanding how MS self-management evolves over the life course and how self-management programmes can help people with MS begin to manage wellness earlier in their lives.

Efficacy, safety, and cost-effectiveness of glatiramer acetate in the treatment of relapsing-remitting multiple sclerosis

The current Multiple Sclerosis (MS) therapeutic landscape is rapidly growing. Glatiramer acetate (GA) remains unique given its non-immunosuppressive mechanism of action as well as its superior long-term safety and sustained efficacy data. In this review, we discuss proposed mechanisms of action of GA. Then we review efficacy data for reduction of relapses and slowing disability as well as long term safety data. Finally we discuss possible future directions of this unique polymer in the treatment of MS.

Factors influencing healthy aging with multiple sclerosis: a qualitative study

PURPOSE

The purpose of this study was to describe the factors influencing healthy aging from the perspective of the older person with multiple sclerosis (MS) in order to build curricula for MS self-management programs.

METHOD

We sourced participants, older than 55 years with MS for more than 20 years, from a database of MS clinic and outpatient rehabilitation visits. Recruitment continued until data saturation was reached (n = 18). Semi-structured interviews explored perspectives on aging and health and lifestyle habits. Demographic, lifestyle and perceived health status information was also gathered. We analyzed the transcribed text for themes and theme relationships.

RESULTS

Work and social engagement, effective and accessible health care, healthy lifestyle habits, and maintaining independence at home were found to be critical proximal factors for healthy aging. The presence of financial flexibility, social support, cognitive and mental health, and resilience provided a supporting foundation to these critical proximal factors. These factors comprised a two-tiered model of healthy aging with MS.

CONCLUSIONS

This two-tiered conceptual model of health aging, based on the perspectives of older persons with MS, provides a potential framework for the development of MS self-management program curricula aimed at optimizing quality of life. Further empirical testing may validate its utility in predicting healthy aging with MS.

Multiple sclerosis affects the frequency content in the vertical ground reaction forces during walking

BACKGROUND

Multiple sclerosis is a progressive neurological disease that results in a high incident of gait disturbance. Exploring the frequency content of the ground reaction forces generated during walking may provide additional insights to gait in patients with multiple sclerosis that could lead to specific tools for differential diagnosis. The purpose of this study was to investigate differences in the frequency content of these forces in an effort to contribute to improved clinical management of this disease.

METHODS

Eighteen patients and eighteen healthy controls walked across a 10 meter long walkway. The anterior-posterior and vertical ground reaction forces generated during the stance phase of gait were evaluated in the frequency domain using fast Fourier transformation. T-tests were utilized for comparison of median frequency, the 99.5% frequency, and the frequency bandwidth between patients and healthy controls and also for comparisons between patients with mild and moderate severity.

FINDINGS

Patients with multiple sclerosis had significantly lower 99.5% frequency (P=0.006) and median frequency (P<0.001) in the vertical ground reaction force. No differences were found in the anterior-posterior reaction force frequency content. There were no differences between patients with mild and moderate severity.

INTERPRETATION

The lower frequency content suggests lesser vertical oscillation of the center of gravity. Lack of differences between severities may suggest presence of differences prior to currently established diagnosis timelines. Analysis of the frequency content may potentially serve to provide earlier diagnostic assessment of this debilitating disease.

Trend for decreasing Multiple Sclerosis Severity Scores (MSSS) with increasing calendar year of enrollment into the New York State Multiple Sclerosis Consortium

Background: Although the natural history of multiple sclerosis has been charted extensively, it is still not known whether the trajectory of disability accumulation has changed in the era of disease-modifying therapies (DMTs).

Objective: The objective of this study was to examine trends in Multiple Sclerosis Severity Score (MSSS) with regard to calendar year of enrollment into the New York State MS Consortium (NYSMSC).

Methods: Distributions of MSSS were calculated for each year of enrollment, from 1996 to 2007. Quantile regression was used in a multivariable analysis to model for conditional distribution of MSSS quantiles as functions of potential confounders.

Results: The cohort consisted of 6238 patients. Mean age at enrollment was 38 years (SD = 10) and mean disease duration was 10.1 years (SD = 7.3); 57% were on DMTs. The quantile regression model of trends in MSSS between 1996 and 2007 controlled for age, sex, ethnicity, diagnostic delay, and disease duration and demonstrated a robust trend toward lower MSSS with increasing year of enrollment. The model-predicted median MSSS at enrollment in 1996 was 5.04 (95% CI, 4.86–5.21), and in 2007 was 3.78 (95%CI, 3.36–4.20; p < 0.001). The downward trend in MSSS during the enrollment period was confirmed by analysis of Expanded Disability Status Scale (EDSS) distributions, adjusted for disease duration, in successive years of enrollment.

Conclusions: The recent enrollees into the NYSMSC had lower MSSSs compared to the earlier enrollees. The apparent slowing in disability accumulation is likely due to a complex combination of factors: advent of DMTs and improvements in MS care, as well as selection, migration, and recall biases.