Tuesday 4 September 2018

Evidence from Iran that wealth is unrelated to MS

Mult Scler Relat Disord. 2018 Aug 23;25:292-296. doi: 10.1016/j.msard.2018.08.019. [Epub ahead of print]

No association between socioeconomic status and risk of multiple sclerosis: A population-based incident case-control study in a developing country.

Abdollahpour I, Nedjat S, Salimi Y, Moradzadeh R, Mansournia MA, Sahraian MA, Shokoohi M.


Evidence on the association between socioeconomic status (SES) and multiple sclerosis (MS) is inconsistent. We examined the association of several indicators of SES with MS in an Iranian population.


We conducted a population-based incident case-control study with 547 incident cases and 1057 general population controls in Iran, 2015. Data was collected using telephone interviews and indicators of SES i.e. parental education, and household SES during adolescence using asset variables. Adjusted odds ratios (AORs) were estimated using multiple logistic regression model.


Parental education levels were not significantly associated with MS development. Household SES during adolescence was insignificantly associated with an increased risk of MS diagnosis (P = 0.575).


We did not identify an association between household SES during adolescence, parental education levels, and a subsequent risk of developing MS in an Iranian population.

In Iran the rates of MS have been sky rocketing. In the capital city, Tehran, between 1989 and 2005 the yearly diagnoses of MS rose from 0.68 per 100,000 to 4.58 per 100,000. By 2009, the incidence rose even further to 9.1 per 100,000 with a prevalence of 73 per 100,000; approaching figures quoted for the UK. Who knows what has led to this sudden change? First and foremost cultural changes need to be factored in. Not being privy to the Iranian lifestyle I must admit that overlaying Western cultural risk factors may not be the correct way to go. But, it goes without saying that over the over the last two decades, like most Eastern nations, Iran has witnessed a dramatic rise in the wealth of the typical worker more in line with Global wealth, and possibly even adoption of certain Western lifestyles.

Socioeconomic status (SES) has received consistent attention as a risk factor for MS, in particular a higher levels of SES have been associated with a greater risk of developing MS, i.e. MS is more prevalent in higher income countries. Although this hasn't been a consistent finding, and in fact the complete opposite has been suggested in more recent studies. Studies which have used educational level as a proxy for SES have found the exact opposite; wherein individuals with a higher educational level were 39% less likely to get MS (Bjørnevik et al., 2016).

Here, Abdollahpour et al. investigate whether SES can be playing a role in the risk of MS in a developing nation, such as Iran. They conducted a population-based case-control study in the capital city Tehran, the most populated region in Iran. Using the Iranian MS Society registry they were able to contact 1057 of PwMS in the registry. They studied parental educational level, assets, participants educational level, and potential confounders (substance abuse and smoking history).

Although, they found that risk of MS was greater in those with illiterate parents and lower in those with University educated parents, this risk was not statistically significant (odds ratio/measure of an association between exposure and outcome was 1.03, CI 0.99-1.07). But, looking at asset values there was an increased but not significant risk in the higher asset groups compared to low asset groups.

In summary, this study did not show that SES was associated with an increased risk of multiple sclerosis. Such studies are often difficult to perform at a population level, in particular owing to lack of full information and the contextual nature of wealth which is forever changing. You might even argue that educational level is not the same as liquidable assets.