Impact of the first Gulf war on multiple sclerosis risk in Kuwait: a quasi-experimental study

OBJECTIVE

It has been reasoned that stressful life events tend to alter immune function thereby increasing the susceptibility to autoimmune diseases including multiple sclerosis (MS). Using the database of Kuwait National MS Registry, this quasi-experimental study assessed the impact of the first Gulf War (Iraqi invasion of Kuwait in 1990) on MS risk in Kuwait.

METHODS

MS incidence data from 1980 to 2019 were obtained from the Kuwait National MS Registry. Annual age-standardized incidence rates (ASIRs) (per 10⁵ person-years) were computed using the World Standard Population as a reference. Interrupted time series analysis with the option of autoregressive order (1) was used to evaluate the impact of the first Gulf War on MS risk by treating 1990 as an intervention year.

RESULTS

Estimated baseline annual ASIR (per 10⁵ person-years) was 0.38 (95% CI: -1.02, 1.78; p = 0.587). MS ASIRs (per 10⁵ person-years) tended to increase significantly every year prior to 1990 by 0.45 (ASIR per 10⁵ person-years = 0.45; 95% CI: 0.15, 0.76; p = 0.005). During the first year of the first Gulf War, there seemed to be a non-significant increase (step change) in ASIRs (per 10⁵ person-years) of MS (ASIR per 10⁵ person-years = 0.85; 95% CI: - 5.16, 6.86; p = 0.775) followed by a non-significant increase in the annual trend in MS ASIRs per 10⁵ person-years (relative to the preintervention trend i.e., the difference between the pre-first Gulf War versus the post-first Gulf War trends) by 0.65 (ASIR per 10⁵ person-years = 0.65; 95% CI: - 0.22, 1.52; p = 0.138). However, a postestimation measure of the post-first Gulf War trend was statistically significant (ASIR per 10⁵ person-years = 1.10; 95% CI: 0.40, 1.80; p = 0.003), which implies that the post-first Gulf War trend in the annual ASIRs (per 10⁵ person-years) inclined to be the same as was the pre-first Gulf War (i.e., counterfactual of the pre-first Gulf War trend in annual ASIRs (per 10⁵ person-years) as if no first Gulf War took place).The Durbin-Watson test statistic (d = 1.89) showed almost non-significant autocorrelations across the time series observations on ASIRs (per 10⁵ person-years).

CONCLUSIONS

This study suggests that the first Gulf War was not significantly associated with the increasing trend in MS risk at population level in Kuwait neither with any short-term change nor with secular trend. Future studies may consider confirming the role of conflict-related stress or other stressful life events in potential exacerbation of MS risk along with unraveling biologically plausible mechanistic pathways.

Multiple sclerosis incidence temporal trend in the Northeast of Iran: Using the Empirical Bayesian method

BACKGROUND

In recent years dramatic changes in multiple sclerosis (MS) incidence have been reported in different provinces in Iran. This study was conducted to assess MS incidence temporal trends from March 21, 2005, to March 20, 2020, and provide a forecast until the end of 2025 in Shahroud county.

METHODS

This longitudinal study was carried out based on the data obtained from the MS registration system in Shahroud county. First, the annual incidence rates were calculated based on the year of diagnosis and smoothed using the Empirical Bayesian Method. Then temporal trends and annual percent change (APC) of MS incidence were analyzed using Joinpoint (JP) regression. Finally, the univariate time series model analysis was used to estimate the MS incidence trend until the end of 2025.

RESULTS

A total of 234 newly diagnosed cases (60 [25.64%] males and 174 [74.36.4%] females) were examined in this study. The mean age of patients at the time of diagnosis was 31.40 ± 3.78. It was 32.01 ± 6.35 and 30.66 ± 4.27 years for males and females, respectively (P<0.22). The mean annual MS incidence was 5.99 ± 1.46, 3.03 ± 0.21, and 8.98 ± 2.79 per 100,000 in overall, males and females respectively. The MS incidence increased significantly from 5.67 (95% CI: 3.63-7.99) in 2005 to 7.58 (95% CI: 5.17-10.28) in 2020 with an APC of 4.5 (2.8 - 6.1). The MS incidence had a non-linear time trend in the study period and the best time trend fitted to the annual MS incidence trend was the non-linear quadratic curve. Based on this model, the annual MS incidence is expected to increase until the end of 2025.

CONCLUSION

Shahroud county is one of the high-risk areas for MS and the increasing trend of MS incidence in it is similar to regional and global changes. This study, also, showed that MS incidence in Shahroud county will be increasing in the coming years.

Prevalence and incidence of multiple sclerosis in Ardabil, Northwest of Iran

BACKGROUND

Multiple sclerosis (MS) epidemiology is studies in many populations; however, studying populations with unique characteristics could provide opportunities to deepen the understanding of the underlying reason of the disease. In this regard, we aimed to study the epidemiology of MS in Ardabil, a province in northwest Iran, where the majority are of Iranian Azerbaijanis.

METHOD

A retrospective population-based study was conducted from 2008 to 2018 in Ardabil, based on the data of Iran's Ministry Of Health. Collected information includes sex, age, age at disease onset, education and type of MS. We used t-test to compare means and chi-square test to analyze the association among variables.

RESULTS

The total number of patients was 760 with 533 (70.13%) females and 227 (29.87%) males. The crude prevalence was 59.37 per 100,000 in 2018 (95% CI: 55.31, 63.73). The crude incidence rate was 7.65 per 100,000 in 2018 (95% CI: 6.28, 9.32). The most frequent educational level was high school diploma (38.36%). The relapsing-remitting (RR) form was the most frequent type of MS (48.16%). The F/M ratio was 2.92:1 and the mean onset age was 33.14 (95% CI: 31.56, 34.72) in 2018, significantly higher in males (P value= 0.01).

CONCLUSION

Ardabil is a medium risk zone of MS. The different ethnicity of its population, climate and environmental features, may explain the factors modulating the risk of MS in similar areas and present windows of opportunity to understand the causes of MS.

Geographic variations of multiple sclerosis in Iran: A population based study

BACKGROUND

The epidemiology of Multiple sclerosis (MS) has changed in recent decades. Considering that the incidence and geographical variations of MS is not well known in Iran. The present study was conducted to investigate the incidence of MS and its geographic variations in Iran.

METHODS

Data from a national registry, coordinated by the Ministry of Health (MOH), were collected for this study. In Iran, all MS patients are eligible to receive care and treatment services based on their records in this registry. Therefore, it seems that the related data are comprehensive with very high coverage, particularly in recent years. In this study, the annual incidence rates were calculated based on year of diagnosis of MS.

RESULTS

In this registry, 32,633 new cases were recorded between 2011 and 2016. After standardized for age, the mean annual incidence rate was 6.5 per 100,000 populations. It was 10.2 and 2.9 in women and men respectively. This incidence ranged from 1.7 to 12.8 in provincial level, with a higher intensity in the central part of the country.

CONCLUSION

It seems that the incidence rate of MS and its ratio in females and males are more or less comparable with the dominant patterns in developed countries, although its variation within the country is very considerable.

Prevalence and Incidence of Multiple Sclerosis in Fars Province, Southern Iran

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system, which is accompanied by significant disabilities. Although there are some published data regarding the epidemiological features of MS in other parts of Iran, scarce data are available about the prevalence and demographic characteristics of MS in Fars province. The current study aimed to address the prevalence and incidence rate of MS as well as the temporal trend of the disease in Fars province, southern Iran.

METHODS

This historical retrospective cohort study was carried out in Fars Multiple Sclerosis Society affiliated with Shiraz University of Medical Sciences. All the consecutive patients who fulfilled 2010 McDonald criteria for definite MS were included in the study. The patients' gender, age at time of diagnosis, education, and clinical course were recorded. The prevalence and incidence rates were also calculated.

RESULTS

This study was conducted on 3,354 patients. Among the patients, 2,689 (80.2%) were female and 665 (19.8%) were male. The female/male ratio was 4.04. The point prevalence rate of the disease was 72.1/100,000 persons in October 2013. This index was 116.5 per 100,000 persons in females (95% CI: 113.4-119.6) and 28.3 per 100,000 persons in males (95% CI: 26.8-29.9). The mean annual incidence rate was 5.2/100,000 from 2002 until 2012.

CONCLUSION

Considering Kurtzke classification, Fars is a high-risk area for MS and women are affected more compared with men. Moreover, the incidence rate sharply increased in the last decade.