Recommendations for observational studies of comorbidity in multiple sclerosis

Comorbidity in US patients with multiple sclerosis

Objective

To assess the trends in the prevalence of comorbidities in US patients with multiple sclerosis (MS), and the association of demographic characteristics with the presence of comorbidities.

Study design

A retrospective analysis was conducted from a sample of 5 million patients from the IMS Health Real World Data Adjudicated Claims – US database.

Methods

Comorbidity in patients with MS was assessed by year (2006–2014), and logistic regression models evaluated the association of age, sex, and region with select comorbidities.

Results

The most common comorbidities from 2006 to 2014 were hyperlipidemia and hypertension (25.9%–29.7% of patients within an individual year), followed by gastrointestinal disease (18.4%–21.2% of patients) and thyroid disease (12.9%–17.1% of patients). The proportion with a claim for hyperlipidemia increased from 2006 to 2009, was stable from 2009 to 2011, and then declined from 2011 to 2014. The proportion with a claim for hypertension generally increased from 2006 to 2013, then declined from 2013 to 2014. The proportion with a claim for gastrointestinal disease, thyroid disease, and anxiety generally increased from 2006 to 2014. Claims for comorbidities were statistically significantly more likely among older age groups (p<0.05), with the exception of anxiety and alcohol abuse, which were statistically significantly less likely among older age groups. Claims for gastrointestinal disease (OR=0.75), thyroid disease (OR=0.36), chronic lung disease (OR=0.76), arthritis (OR=0.71), anxiety (OR=0.63), and depression (OR=0.69) were statistically significantly less likely among males versus females (all p<0.05). Claims for hyperlipidemia (OR=1.39), hypertension (OR=1.25), diabetes (OR=1.31), and alcohol abuse (OR=2.41) were significantly more likely among males (p<0.05). Many comorbidity claims were statistically significantly more likely in the Northeast and South compared with the Midwest and West.

Conclusion

This study provides select comorbidity claims estimates in US patients with MS, and thus highlights the importance of comprehensive patient care approaches.

Effects of physical comorbidities on disability progression in multiple sclerosis

OBJECTIVE

To examine the association between physical comorbidities and disability progression in multiple sclerosis (MS).

METHODS

We conducted a retrospective cohort study using linked health administrative and clinical databases in 2 Canadian provinces. Participants included adults with incident MS between 1990 and 2010 who entered the cohort at their MS symptom onset date. Comorbidity status was identified with validated algorithms for health administrative data and was measured during the 1 year before study entry and throughout the study period. The outcome was the Expanded Disability Status Scale (EDSS) score as recorded at each clinic visit. We used generalized estimating equations to examine the association between physical comorbidities and EDSS scores over time, adjusting for sex, age, cohort entry year, use of disease-modifying drugs, disease course, and socioeconomic status. Meta-analyses were used to estimate overall effects across the 2 provinces.

RESULTS

We identified 3,166 individuals with incident MS. Physical comorbidity was associated with disability; with each additional comorbidity, there was a mean increase in the EDSS score of 0.18 (95% confidence interval [CI] 0.09-0.28). Among specific comorbidities, the presence of ischemic heart disease (IHD) or epilepsy was associated with higher EDSS scores (IHD 0.31, 95% CI 0.01-0.61; epilepsy 0.68, 95% CI 0.11-1.26).

CONCLUSIONS

Physical comorbidities are associated with an apparent increase in MS disability progression. Appropriate management of comorbidities needs to be determined to optimize outcomes.

Challenge of progressive multiple sclerosis therapy

PURPOSE OF REVIEW

Understanding the mechanisms underlying progression in multiple sclerosis (MS) and identifying appropriate therapeutic targets is a key challenge facing the MS community. This challenge has been championed internationally by organizations such as the Progressive MS Alliance, which has raised the profile of progressive MS and identified the key obstacles to treatment. This review will outline the considerable progress against these challenges.

RECENT FINDINGS

New insights into mechanisms underlying progression have opened up potential therapeutic opportunities. This has been complemented by ongoing validation of clinical and imaging outcomes for Phase II trials of progression, coupled with the development of innovative trial designs. The field has been greatly encouraged by recent positive Phase III trials in both primary and secondary progressive MS, albeit with modest benefit. Early trials of neuroprotection and repair have provided important new data with which to drive the field. Improving symptom management and advancing rehabilitation approaches, critical for this patient population which, taken together with identifying and managing comorbidities and risk factors, has an appreciable impact on health-related quality of life.

SUMMARY

Raising the profile of progressive MS has resulted in the first effective treatments with the promise of more to come.

Comorbidity increases the risk of relapse in multiple sclerosis: A prospective study

OBJECTIVE

To evaluate the association between comorbidity and relapse rate in individuals with multiple sclerosis (MS).

METHODS

We recruited individuals with prevalent relapsing-onset MS from 4 Canadian MS Clinics to participate in a 2-year prospective multicenter cohort study involving cross-sectional assessment of comorbidities and relapses. Comorbidities were recorded using questionnaires, and relapses were captured from medical records at each visit. The association between comorbidities at baseline and relapse rate over the subsequent 2-year follow-up period was examined using Poisson regression, adjusting for age, sex, disability, disease duration, and treatment status.

RESULTS

Of 885 participants, 678 (76.6%) were women, averaging age 48.2 years at baseline. Anxiety (40.2%), depression (21.1%), hypertension (17.7%), migraine (18.1%), and hyperlipidemia (11.9%) were the most prevalent comorbidities. The frequency of participants experiencing relapses remained constant at 14.9% and 13.2% in years 1 and 2 post-baseline. After adjustment, participants reporting ≥3 baseline comorbidities (relative to none) had a higher relapse rate over the subsequent 2 years (adjusted rate ratio 1.45, 95% confidence interval [CI] 1.00-2.08). Migraine and hyperlipidemia were associated with increased relapse rate (adjusted rate ratio 1.38; 95% CI 1.01-1.89 and 1.67; 95% CI 1.07-2.61, respectively).

CONCLUSIONS

Individuals with migraine, hyperlipidemia, or a high comorbidity burden (3 or more conditions) had an increased relapse rate over 2 years. These findings have potential implications for understanding the pathophysiology of MS relapses, and suggest that closer monitoring of individuals with specific or multiple comorbidities may be needed. Future research is needed to understand if the presence of comorbidity warrants a tailored approach to MS management.

Assessing association of comorbidities with treatment choice and persistence in MS

Objective:

To assess whether the presence of concomitant diseases at multiple sclerosis (MS) diagnosis is associated with the choice and the treatment persistence in an Italian MS cohort.

Methods:

We included newly diagnosed patients (2010–2016) followed in 20 MS centers and collected demographic and clinical data. We evaluated baseline factors related to the presence of comorbidities and the association between comorbidities and the clinical course of MS and the time to the first treatment switch.

Results:

The study cohort included 2,076 patients. Data on comorbidities were available for 1,877/2,076 patients (90.4%). A total of 449/1,877 (23.9%) patients had at least 1 comorbidity at MS diagnosis. Age at diagnosis (odds ratio 1.05, 95% confidence interval [CI] 1.04–1.06; p < 0.001) was the only baseline factor independently related to the presence of comorbidities. Comorbidities were not significantly associated with the choice of the first disease-modifying treatment, but were significantly associated with higher risk to switch from the first treatment due to intolerance (hazard ratio 1.42, CI 1.07–1.87; p = 0.014). Association of comorbidities with risk of switching for intolerance was significantly heterogeneous among treatments (interferon β, glatiramer acetate, natalizumab, or fingolimod; interaction test, p = 0.04).

Conclusions:

Comorbidities at diagnosis should be taken into account at the first treatment choice because they are associated with lower persistence on treatment.

Comorbidity in multiple sclerosis is associated with diagnostic delays and increased mortality

OBJECTIVE

To investigate the effect of chronic comorbidity on the time of diagnosis of multiple sclerosis (MS) and on mortality in MS.

METHODS

We conducted a population-based, nationwide cohort study including all incident MS cases in Denmark with first MS symptom between 1980 and 2005. To investigate the time of diagnosis, we compared individuals with and without chronic comorbidity using multinomial logistic regression. To investigate mortality, we used Cox regression with time-dependent covariates, following study participants from clinical MS onset until endpoint (death) or to the end of the study, censuring at emigration.

RESULTS

We identified 8,947 individuals with clinical onset of MS between 1980 and 2005. In the study of time of diagnosis, we found statistically significant odds ratios for longer diagnostic delays with cerebrovascular comorbidity (2.01 [1.44-2.80]; <0.0005), cardiovascular comorbidity (4.04 [2.78-5.87]; <0.0005), lung comorbidity (1.93 [1.42-2.62]; <0.0005), diabetes comorbidity (1.78 [1.04-3.06]; 0.035), and cancer comorbidity (2.10 [1.20-3.67]; 0.009). In the mortality study, we found higher hazard ratios with psychiatric comorbidity (2.42 [1.67-3.01]; <0.0005), cerebrovascular comorbidity (2.47 [2.05-2.79]; <0.0005), cardiovascular comorbidity (1.68 [1.39-2.03]; <0.0005), lung comorbidity (1.23 [1.01-1.50]; 0.036), diabetes comorbidity (1.39 [1.05-1.85]; 0.021), cancer comorbidity (3.51 [2.94-4.19]; <0.0005), and Parkinson disease comorbidity (2.85 [1.34-6.06]; 0.007).

CONCLUSIONS

An increased awareness of both the necessity of neurologic evaluation of new neurologic symptoms in persons with preexisting chronic disease and of optimum treatment of comorbidity in MS is critical.

Hospitalization is associated with subsequent disability in multiple sclerosis

BACKGROUND

Although an increasing amount of research has evaluated interactions between MS and comorbid chronic disease, few data exist regarding the interactions between MS and acute illness. As compared to age and sex-matched persons without MS, persons with MS experience higher rates of hospitalization and critical illness, and higher mortality rates and health care utilization following critical illness. We aimed to determine whether acute illness requiring hospitalization is associated with progression of multiple sclerosis (MS).

METHODS

We conducted this population-based, retrospective cohort study by linking data from the regional MS Clinic in Calgary, Canada with the Canadian Discharge Abstract Database to identify non-obstetric hospitalizations. We included individuals with a confirmed diagnosis of MS, at least one recorded Expanded Disability Status Scale (EDSS) measurement, and known age of symptom onset of age 10 years or older. Using data from 2009 to 2014, we used generalized linear models with generalized estimating equations to establish the association within individuals between hospitalization and the time course of MS-related disability (as measured by the EDSS), adjusting for sex, age, disease course at onset, and use of disease-modifying therapies.

RESULTS

We included 2104 individuals with MS in the analysis, who had a median of 4 EDSS measurements each. Of these 491 (23.3%) had at least one hospitalization. Most subjects were female, with a relapsing disease course at onset, and a mean (SD) age at symptom onset of 33.0 (10.0) years. The underlying rate of disability progression averaged 0.9 EDSS points per decade. Following hospitalization, there was a step increase in EDSS, averaging 0.23 points, equivalent to 2.5 years of time-related disease progression. Hospitalization did not alter the subsequent temporal rate of disability progression. The findings did not differ in those hospitalized for MS versus other reasons.

CONCLUSIONS

Acute illness requiring hospitalization is associated with a worsening of MS-related disability.

A population-based cohort study suggests an increased risk of multiple sclerosis incidence in patients with type 2 diabetes mellitus

Background

To prospectively investigate the incidence and relative risks of multiple sclerosis (MS) in patients with type 2 diabetes (T2DM).

Materials and methods

Patients with T2DM (n = 614,623) and age- and sex-matched controls (n = 614,021) were followed from 2000 to 2008 to identify cases of newly diagnosed MS (ICD-9-CM: 340). The person-year approach with Poisson assumption was used to evaluate the incidence density. We estimated the covariate-adjusted hazard ratio (HR) of MS incidence in relation to T2DM diabetes using a multiple Cox proportional hazard regression model.

Results

Over 9 years of follow-up, 175 T2DM patients were newly diagnosed with MS, and 114 matched controls had the same first-ever diagnosis, representing a covariate-adjusted HR of 1.44 (95% confidence interval [CI], 1.08–1.94). The sex-specific adjusted HR for both men and women with T2DM was also elevated at 1.34 (95% CI, 0.81–2.23) and 1.51 (95% CI, 1.05–2.19), respectively. Women aged ≤50 years had the greatest risk of MS (HR 2.16; 95% CI, 1.02–4.59).

Conclusion

This study demonstrated a moderate but significant association of T2DM with MS incidence, and the association was not confounded by socio-demographic characteristics or certain MS-related co-morbidities.

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Risk ratio of incident multiple sclerosis (MS) in T2DM patients was 1.44.

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Risk ratio of incident MS was highest in women aged <50 years.

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The PAR% for T2DM in the MS incidence was estimated at 2.55%.

Inverse comorbidity in multiple sclerosis: Findings in a complete nationwide cohort

BACKGROUND

Inverse comorbidity is disease occurring at lower rates than expected among persons with a given index disease. The objective was to identify inverse comorbidity in MS.

METHODS

We performed a combined case-control and cohort study in a total nationwide cohort of cases with clinical onset of MS 1980-2005. We randomly matched each MS-case with five population controls. Comorbidity data were obtained from multiple, independent nationwide registries. Cases and controls were followed from January 1977 to the index date, and from the index date through December 2012. We controlled for false discovery rate and investigated each of eight pre-specified comorbidity categories: psychiatric, cerebrovascular, cardiovascular, lung, and autoimmune comorbidities, diabetes, cancer, and Parkinson's disease.

RESULTS

A total of 8947 MS-cases and 44,735 controls were eligible for inclusion. We found no inverse associations with MS before the index date. After the index date, we found a decreased occurrence of chronic lung disease (asthma and chronic obstructive pulmonary disease) (HR 0.80 (95% CI 0.75-0.86, p<0.00025)) and overall cancer (HR 0.88 (95% CI 0.81-0.95, p=0.0005)) among MS-cases.

CONCLUSION

This study showed a decreased risk of cancers and pulmonary diseases after onset of MS. Identification of inverse comorbidity and of its underlying mechanisms may provide important new entry points into the understanding of MS.

Influence of hypertension, diabetes, hyperlipidemia, and obstructive lung disease on multiple sclerosis disease course

Background:

Comorbidities are known to affect multiple sclerosis (MS) patients in a number of ways, including delaying time to diagnosis and reducing health-related quality of life.

Objective:

To determine the impact of hypertension, hyperlipidemia, diabetes mellitus, and obstructive lung disease on disease course in MS patients.

Methods:

The Knowledge Program is a database linked to our electronic medical record allowing capture of patient and clinician reported outcomes. Through Knowledge Program query and chart review, we identified all relapsing-remitting MS patients seen between 1 January 2010 and 29 May 2012 and acquired their magnetic resonance imaging (MRI) results and comorbidities. Linear and logistic regression models with adjustment for important covariates were used to determine whether the comorbidities affected outcomes over a 3-year period.

Results:

Hypertension, diabetes, and obstructive lung disease, but not hyperlipidemia, impacted clinical outcomes, including walking speed, self-reported disability, and depression. Hypertension had the greatest effect. The presence of multiple comorbidities had a cumulative effect on clinical outcomes. MRI outcomes were unaffected by comorbidities.

Conclusion:

This 3-year longitudinal study revealed that all comorbidities tested except hyperlipidemia impacted clinical outcomes and a cumulative effect with multiple comorbidities was observed. Consideration of comorbid conditions is essential in MS patient care.