Journal of Applied Sciences and Clinical Practice

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 2  |  Issue : 3  |  Page : 74--78

Antiviral therapy for herpes simplex virus encephalitis: Systematic review and meta-analysis of randomized control trials


Sridhar Amalakanti1, Sri Harsha Boppana1, Nagarjuna Sivaraj2, Kesava Venkata Raman Arepalli1, Tarun Kumar Suvvari3,  
1 Department of General Medicine, Great Eastern Medical School and Hospital, Srikakulam, Andhra Pradesh, India
2 Central Research Lab, Great Eastern Medical School and Hospital, Srikakulam, Andhra Pradesh, India
3 Dr. NTR University of Health Sciences, Vijayawada, Andhra Pradesh, India

Correspondence Address:
Dr. Sridhar Amalakanti
Department of General Medicine, Great Eastern Medical School and Hospital, Srikakulam, Andhra Pradesh
India

Abstract

Background: Herpes simplex virus (HSV) infection of the brain is treated with antiviral drugs such as acyclovir. A summary of randomized control trials (RCTs) of antiviral drugs against HSV encephalitis has not been put forward yet. We aimed to determine the effect of antiviral agents in treating HSV encephalitis on mortality and neurological sequelae at approximately 2 years. The secondary objective was to assess the adverse effect of antiviral agents on the patients. Materials and Methods: RCTs were identified by searching PUBMED, European Medicines Agency ( EMA ), USFDA, US Clinical trials, Elsevier database, and Cochrane website and the reference lists of published trials. Randomized controlled trials of antiviral therapy in biologically proven HSV infection were included in the study. Results: A total of 5 studies met the criteria. The first study was published in 1980 and the latest was in 2015. All the studies used acyclovir/valacyclovir or vidarabine. Three studies compared acyclovir and vidarabine, one study was placebo-controlled vidarabine trial and another one was a placebo-controlled trial of long-term valacyclovir therapy. Acyclovir improved mortality and lowered the incidence of neurological sequelae. There was no significant reduction in the risk of mortality with vidarabine therapy. Conclusion: Trial evidence suggests that acyclovir decreases mortality and morbidity in acute HSV encephalitis.



How to cite this article:
Amalakanti S, Boppana SH, Sivaraj N, Raman Arepalli KV, Suvvari TK. Antiviral therapy for herpes simplex virus encephalitis: Systematic review and meta-analysis of randomized control trials.J Appl Sci Clin Pract 2021;2:74-78


How to cite this URL:
Amalakanti S, Boppana SH, Sivaraj N, Raman Arepalli KV, Suvvari TK. Antiviral therapy for herpes simplex virus encephalitis: Systematic review and meta-analysis of randomized control trials. J Appl Sci Clin Pract [serial online] 2021 [cited 2021 Nov 27 ];2:74-78
Available from: http://www.jascp.com/text.asp?2021/2/3/74/326722


Full Text



 Introduction



Herpes simplex encephalitis is a severe rapidly fatal viral infection of the brain. It is the most common cause of sporadic infectious encephalitis. It accounts for up to 20% of all cases of acute encephalitis.[1],[2],[3] A few antiviral drugs have shown definitive recovery in patients afflicted with herpes simplex virus (HSV) encephalitis, but a comprehensive meta-analysis of the trials of antiviral drugs against herpes encephalitis is lacking. We analyzed the published work on antiviral treatment in HSV encephalitis and present the summary.

 Materials and Methods



We extracted data from published randomized controlled trials involving HSV patients treated with antiviral drugs following PRISMA guidelines [Figure 1]. Data were retrieved on January 12, 2019, using search terms in PUBMED. The keywords used were described below.{Figure 1}

(“encephalitis, herpes simplex” [MeSH Terms] OR (“encephalitis” [All Fields] AND “herpes” [All Fields] AND “simplex” [All Fields]) OR “herpes simplex encephalitis” [All Fields] OR (“herpes” [All Fields] AND “simplex” [All Fields] AND “encephalitis” [All Fields])) AND (Randomized Controlled Trial [ptyp] OR Controlled Clinical Trial [ptyp] OR Clinical Trial [ptyp] OR systematic [sb] OR Meta-Analysis [ptyp] OR Comparative Study [ptyp]) which yielded 309 studies(“herpes simplex” [MeSH Terms] OR (“herpes” [All Fields] AND “simplex” [All Fields]) OR “herpes simplex” [All Fields]) AND (Randomized Controlled Trial [ptyp] OR Controlled Clinical Trial [ptyp] OR Clinical Trial [ptyp] OR systematic [sb] OR Meta-Analysis [ptyp] OR Comparative Study [ptyp]) which yielded 5200 studies(“encephalitis, herpes simplex” [MeSH Terms] OR (“encephalitis” [All Fields] AND “herpes” [All Fields] AND “simplex” [All Fields]) OR “herpes simplex encephalitis” [All Fields] OR (“herpes” [All Fields] AND “simplex” [All Fields] AND “encephalitis” [All Fields])) AND Meta-Analysis [ptyp] which yielded three studies.

We searched European medical agency website (http://www.ema.europa.eu/ema/index.jsp?curl = search.jspandq = herpes + simplex + enc ephalitis + andbtnG = Searchandmid) and retrieved 129 itemsWe also searched USFDA website (https://search.usa.gov/search?utf8=%E2%9C%93andaffiliate = fdaandquery = herpes + simplex+ encephalitis + andcommit = Search) and recorded 56 entriesFrom the US clinical trials website (https://clinicaltrials.gov/ct2/results?cond =herpes + simplex + encephalitis + andterm = andcntry =andstate = andcity = anddist), we obtained three recordsElsevier database (https://www.sciencedirect.com/search?qs=herpes%20simplex%20encephalitisandshow = 25andsortBy=relevanceandarticleTypes = FLAandlastSelectedFacet = articleypes) returned 5399 resultsThe Cochrane website (https://community.cochrane.org/search/all/herpes%20simplex%20encephalitis%20)showed nine related records.

We searched the bibliographies of the selected studies and included studies only if they were randomized controlled trials on patients with herpes simplex encephalitis. The outcome measures which we considered were mortality, adverse drug reactions and neurological sequelae. Data were retrieved independently by the two authors and any disagreement was resolved by consensus.

Statistical methods

We compared the outcome measures between the interventions by assessing relative risk (RR) with 95% confidence intervals. All analyses were performed by MS Excel 2007 and RevMan software.

 Results



A total of 5 studies met the criteria. The first study was published in 1980[4] and the latest was in 2015.[5] All the studies used acyclovir/valacyclovir or vidarabine. Three studies[6],[7],[8] compared acyclovir and vidarabine, out of which, the 1991 study[8] included only children below 1 month of age. Among the other two, one study[4] was a placebo-controlled vidarabine trial in neonates and another one[5] was a placebo-controlled trial of long-term valacyclovir therapy after IV acyclovir for acute treatment. We found no randomized placebo-controlled trials of acyclovir for HSV encephalitis.

There are minor differences between the three studies comparing acyclovir with vidarabine. In the 1984 study,[6] the dose of acyclovir was lesser when compared to the other two studies 10 mg/kg versus 30 mg/kg thrice daily. The 1986 study[7] was not blinded and the technique of randomization was not mentioned. The 1991 study[8] used a higher dose of vidarabine compared to the other two studies 30 mg/kg versus 15 mg/kg twice daily.

Ninety-four patients had received acyclovir and 99 patients received vidarabine [Table 1]. Acyclovir treatment resulted in lesser mortality RR 0.53, 95% confidence interval (CI) 0.33, 0.85, P = 0.008 [Figure 2] and fewer adverse drug reactions RR 0.56, 95% CI 0.41, 0.78, P = 0.0005 [Figure 3] than vidarabine therapy. Gastrointestinal events were the more common adverse effects with both the drugs [Table 2]. The proportion of postencephalitis neurological sequelae were similar [Figure 4] with both the treatments RR 0.59, 95% CI: 0.59, 1.09, and P = 0.15. A statistically significant difference in mortality [Figure 5], adverse effects [Figure 6], or neurological sequelae did not occur with vidarabine treatment in comparison with placebo. The long-term treatment study[5] concluded that, after standard treatment with intravenous acyclovir, an additional 3-month course of oral 6 g daily of valacyclovir therapy was of little benefit in herpes simplex encephalitis patients.{Table 1}{Figure 2}{Figure 3}{Table 2}{Figure 4}{Figure 5}{Figure 6}

 Discussion



Our review of randomized controlled trials of antiviral drugs against herpes simplex encephalitis showed that acyclovir has a more favorable profile when compared to vidarabine in terms of mortality and adverse effects but not residual neurological sequelae. However, the placebo-controlled vidarabine trial shows no advantage of the drug in herpes simplex encephalitis; also chronic treatment with valacyclovir was not useful. Three studies comparing acyclovir and vidarabine show clear differences in mortality and adverse events with the treatment. The differences in terms of residual neurological sequelae were much more modest. Presumably, other factors such as age and speed of institution of treatment might have affected this outcome. The study comparing vidarabine and placebo included only thirty patients in each arm. The small sample size needs to be borne in mind when considering the equivocal conclusion of the study.

A previous review of antiviral drugs against HSV infection in neonates seconded their efficacy and beneficial effect. However, it could not find any superiority of acyclovir over vidarabine. Our review encompassing all age groups shows that acyclovir is beneficial in herpes simplex encephalitis. Vidarabine has no significant effect on the course of the illness. There is a lack of large-scale randomized controlled trials of the antiviral drugs against HSV encephalitis. Many other drugs have been shown to be successful against herpes simplex in randomized controlled trials. Many other drugs have been shown to be successful against herpes simplex in randomized controlled trials. Examples include Ganciclovir and steroids against keratitis,[9],[10] famciclovir and alpha interferon against genital herpes,[11],[12] foscarnet and ascorbic acid against mucocutaneous lesions.[13],[14] So, there is scope for trials with the above drugs in herpes encephalitis also. These studies showed that gastrointestinal events are the commonest adverse effects. This data also thus suggests a potential arena for fine tuning the drugs like acyclovir and vidarabine.

 Conclusion



Evidence from trials suggests that acyclovir decreases mortality and morbidity in acute HSV encephalitis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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