Gold J, Raph Goldacre R, Hubert Maruszak, Giovannoni G, Yeates D, Goldacre M. HIV and lower risk of multiple sclerosis: beginning to unravel a mystery using a record-linked database studyJ Neurol Neurosurg Psychiatry 2014;0:1–4. doi:10.1136/jnnp-2014-307932 1
Objectives: Even though multiple sclerosis (MS) and human immunodeficiency virus (HIV) infection are well-documented conditions in clinical medicine, there is only a single case report of a patient with MS and HIV treated with HIV anti-retroviral therapies. In this report, the patient’s MS symptoms resolved completely after starting combination anti retroviral therapy and remain subsided for more than 12 years. Authors hypothesised that because the pathogenesis of MS has been linked to human endogenous retroviruses, anti-retroviral therapy for HIV may be coincidentally treating or preventing progression of MS. This led researchers from Denmark to conduct an epidemiological study on the incidence of MS in a newly diagnosed HIV population (5018 HIV cases compared with 50 149 controls followed for 31 875 and 393 871 person-years, respectively). The incidence ratio for an HIV patient acquiring MS was low at 0.3 (95% CI 0.04 to 2.20) but did not reach statistical signiﬁcance possibly due to the relatively small numbers in both groups. Our study was designed to further investigate the possible association between HIV and MS. Methods We conducted a comparative cohort study accessing one of the world’s largest linked medical data sets with a cohort of 21 207 HIV-positive patients and 5 298 496 controls stratiﬁed by age, sex, year of ﬁrst hospital admission, region of residence and socioeconomic status and ‘followed up’ by record linkage.
Results Overall, the rate ratio of developing MS in people with HIV, relative to those without HIV, was 0.38 (95% CI 0.15 to 0.79).
Conclusions HIV infection is associated with a signiﬁcantly decreased risk of developing MS. Mechanisms of this observed possibly protective association may include immunosuppression induced by chronic HIV infection and anti-retroviral medications.
Following the case of an HIV positive man with MS, whose MS symptoms appeared to disappear for more than 12 years after anti-retroviral treatment for HIV, a Danish research team attempted to find out if anti-retroviral drugs might treat or slow the progression of MS. Their results suggested this might be a possibility, but the numbers were too small to reach statistical significance, prompting the ProfGs to carry out a much larger comparative study.
Team G paired up with Ben Goldarce‘s dad and they did this by looking at episodes of hospital care between 1999 and 2011 in England.
In all, more than 21,000 people infected with HIV were treated during this period as were almost 5.3 million people treated for minor conditions or injuries who were not infected with HIV. The development of MS was tracked in all the participants for an average of between 6.5 and 7.5 years, in the context of the actual number of cases versus the expected number of cases in the population.
Compared with those who did not have HIV, those who did were 62% less likely to develop MS, based on 7 actual diagnoses of MS during that period versus the 18 that would be expected to develop. The degree of protection seemingly conferred by HIV seemed to increase the more time elapsed between a diagnosis of HIV and one of MS.
After more than a year between the two, HIV positive patients were 75% less likely to develop MS, based on four actual diagnoses versus the 16 that would be expected; after more than five years this increased to 85%, based on one actual case versus the 6.5 that would be expected.
The findings back those of the Danish researchers, but with the crucial difference being that they are statistically significant.
These findings are speculative rather than definitive because the study is observational, added to which there is no information on whether the HIV positive participants had taken anti-retroviral drugs, or for how long. The demographics of HIV and MS in UK are not identical but this study does look at very big numbers of people.
Why not get it from the Horse’s Mouth (or should this be the Kangeroo’s mouth) and listen to ProfG Down Under on “Inside Health” (Get it ONLINE (This link will work in UK, elsewhere not sure) or on the radio) on Tuesday 5th August 2014
Inside Health is on BBC Radio 4 Tonight at 21.00 BST, repeated tomorrow at 15.30 BST.
Sorry for the confusion!!
The story has cropped up in unusual places