Larger social network effective size correlated with better physical function, while network constraint correlated with worse physical function in those with multiple sclerosis.
Results from a cross-sectional study revealed that patients with multiple sclerosis (MS) with close-knit personal social networks had worse function than those with open social networks, highlighting the importance of personal social networks as an environmental factor associated with physical function in patients with MS.
Led by Seth N. Levin, MD, neurologist, New York-Presbyterian Columbia University Irving Medical Center, and colleagues, a meta-analysis of 2 cohorts showed that higher network constraint, a measure of tightly-bound networks, was associated with worse physical function (ß = —0.163 [±0.047]; P <.001). In contrast, larger network effective size, a measure of clustered groups in the network, correlated with better physical function (ß = 0.134 [±0.046]; P = .003).
Higher scores on the Multiple Sclerosis Rating Scale-Revised (MSRS-R) indicated greater neurological dysfunction and disability. Greater network constraint correlated with a higher MSRS-R score (ß = 0.134 [±0.046]; P = .004), whereas larger network effective size was associated with lower MSRS-R score in the meta-analysis (ß = —0.099 [±0.046]; P = .030). The associations of overall network structure with physical function were independent of typical risk factors for disability, including age, gender, race, and disease duration.
The 2-part analysis looked at the association of personal network structure and composition with physical function, with higher scores on the National Institutes of Health (NIH) Patient-Reported Outcomes Measurement Information System (PROMIS) indicating better overall physical function. Levin and colleagues used a permutation-based omnibus test to examine the presence of an excess of associations for either of these categories with the PROMIS T-score.
The distribution of P-values in the omnibus test was significantly greater than chance for network structure (P = .002) but was only suggestive (P = .047) for network composition. The second stage of analysis examined the relationship of each structural metric with the PROMIS T-score. Results showed that a larger network effective size (ß = 0.170 [±0.062]; P = .006) correlated with better physical function, while network constraint correlated with worse physical function (ß = —0.206 [±0.058]; P <.001).
Another method Levin et al. used was to assess whether structural network associations were unique to physical function as measured by PROMIS. The investigators examined the requirement for an assistive device for distances greater than 25 feet as an indicator of the severity of gait impairment. They found in the meta-analysis that for every 1 standard deviation (SD) increase in social network constraint, the odds of severe gait impairment were significantly higher (odds ratio [OR], 1.46; 95% CI, 1.12—1.90; P = .005).
The study analyzed data from 2 academic MS centers, center 1 serving as discovery group (n = 283), and center 2 as the extension group (n = 163). The discovery group was comprised of 81% women, 96% non-Hispanic European, 78% relapsing MS, average age 50 (SD, 12.4) years, with mean disease duration 17 (SD, 12.3) years. On the other hand, the extension group contained patients who were younger, more racially diverse, less physically disabled, and had shorter disease duration.
The investigators noted that social environment is among the many factors that can contribute towards increased disability in those with MS. Social networks range from small, close-knit cohorts of family and friends, to large clusters of loosely connected acquaintances. Those who maintain the latter of the 2 may enable the flow of novel information and be accessible to a wider range of different resources, and ultimately may have a favorable impact on health outcomes where early symptom recognition and access to new therapies are beneficial.
Social network measurements were quantified by a questionnaire that asked participants to identify people whom they had discussed important matters, socialized, or sought support in the last 3 months. Investigators then explored the connections among all persons in the network and then finally evaluated the characteristics and health habits of each network member. PROMIS physical function scale (0—100, mean 50 for US general population) was used as the primary outcome.
Levin and colleagues noted that future longitudinal studies using parallel clinical and biomarker assessments are needed to explore the possibility of a causal relationship between effectively small, constrained networks and physical impairment in MS.
Levin SN, Riley CS, Dhand A, et al. Association of social network structure and physical function in patients with multiple sclerosis. Neurology. Published online August 7, 2020. doi: 10.1212/WNL.0000000000010460.