有藥愛行為的男同志較其他男同志在愛滋新感染診斷上的可能達五倍
資料來源：Aidsmap News, Roger Pebody，發佈時間：2018年5月23日，財團法人台灣紅絲帶基金會編譯
根據本周出版的HIV Medicine於倫敦調查之數據，在13個月的隨訪期內曾參與藥愛（使用特定藥物來增強或促進性行為）的男同性戀和雙性戀男性，其更有可能被診斷為愛滋病毒新感的可能性達五倍，更有可能被診斷感染C型肝炎達九倍，而更可能被診斷感染性傳染病（STI）達四倍。
倫敦聖喬治大學醫院的Mark Pakianathan博士及其同事說：「這是首次發表的研究顯示藥愛行為的披露與新的HIV診斷之間存在顯著關聯」。他們說，臨床醫生和公共衛生官員應該利用這項研究結果來確定一個特別容易受到愛滋病毒感染的人群，他們可能成為暴露前預防投藥（PrEP）和其他預防介入措施的目標。
在2014年6月至2015年7月期間，在聖喬治的性健康照護的日常看診期間，1,840名男同性戀和雙性戀男性被問及有關精神健康、物質使用和藥愛等問題。他們的年齡從14歲到82歲不等，但中位數為34歲；其中僅有不到三分之一的人在英國以外地方出生，且該群體具有種族多樣性。目前有286名男性（佔所有男性的16.5％）報告有藥愛行為。
最常用於藥受的藥物是4-甲基甲基卡西酮（喵喵，198名男性），G水如GHB / GBL（152名男性），甲基安非他命（126名男性），古柯鹼（54名男性），其他安非他命類藥物（36名男性）和愷他命（22名男性）。值得注意的是，聖喬治研究人員對藥愛的定義比其他的一些團體還更廣泛，他們通常僅將其定義為在性行為時使用前三種藥物。
這些男性通常同時使用多種藥物。其中有 74名男性報告曾採注射方式用藥。
而在2014年或2015年間未曾報告有藥愛行為的男性中，有1.8％的人被診斷為新感染HIV，而在參與藥愛的男性屬於這種情況為8.6％。在多變量分析中（考慮了一系列影響HIV感染的其他因素），藥愛與感染HIV有關風險增加了5倍（勝算比為5.1,95％的信賴區間為2.6-10.1）。
研究人員評論說，藥愛過程可能持續數天，並可能與多個性伴侶發生粘膜創傷性行為。基於此人群中愛滋病毒感染的高發率，在藥愛上遭遇到的性伴侶有可能是最近才剛感染到愛滋病毒的人，且尚未被診斷出來並具有極高的病毒載量。
在未曾報告藥愛行為的男性中C型肝炎新診斷的發生率為0.2％，而有藥愛的男性則為2.8％（共計11人）。在多變量分析中，這相當於增加了九倍風險（勝算比為9.2， 95％的信賴區間為2.3-36.3）。
同樣，在涉及藥愛的男性中，性傳播疾病感染的診斷也有所提高。所有性病感染（勝算比為3.5），直腸性病感染（4.5）和急性細菌性性病感染（3.9）等都是如此。
研究人員說，接受性健康服務的同性戀和雙性戀男性應該進行是否曾涉入藥愛行為之評估。「藥愛行為的披露應該對健康促進、降低傷害和健康福址之介入等的促進上有所助益」。
Gay men having chemsex are five times more likely to have a new HIV diagnosis than other gay men
Aidsmap News, Roger Pebody, Published: 23 May 2018
Gay and bisexual men who reported engaging in chemsex (the use of specific drugs to enhance or facilitate sex) were five times more likely to be newly diagnosed with HIV, nine times more likely to be diagnosed with hepatitis C and four times more likely to be diagnosed with a sexually transmitted infection (STI) during a 13-month follow-up period, according to London data published this week in HIV Medicine.
“This is the first published study to demonstrate a significant association between chemsex disclosure and new HIV diagnosis,” said Dr Mark Pakianathan and colleagues at St George’s University Hospital, London. Clinicians and public health officials should use the findings to identify a population particularly vulnerable to HIV acquisition who could be targeted for pre-exposure prophylaxis (PrEP) and other prevention interventions, they say.
During routine appointments for sexual health care at St George’s between June 2014 and July 2015, 1840 gay and bisexual men were asked questions about mental health, substance use and chemsex. (A previous aidsmap.com article reported on harms associated with chemsex.) Their ages ranged from 14 to 82 years, but the median was 34. Just under a third were born outside the UK and the cohort was ethnically diverse.
Currently engaging in chemsex was reported by 286 men (16.5% of all men).
Drugs most commonly used for chemsex were mephedrone (198 men), GHB/GBL (152 men), crystal methamphetamine (126 men), cocaine (54 men), other amphetamines (36 men) and ketamine (22 men). Of note, the St George’s researchers used a wider definition of chemsex than some other groups, who define it as only the use of the first three drugs in a sexual context.
Men often used more than one drug at the same time. Injecting drug use was reported by 74 men.
Whereas 1.8% of men who did not report chemsex had a new HIV diagnosis during 2014 or 2015, this was the case for 8.6% of men who were involved in chemsex. In multivariate analysis (which took into account a range of other factors which influence HIV infection), chemsex was associated with a fivefold increase in the risk of HIV infection (adjusted odds ratio 5.1, 95% confidence interval 2.6-10.1).
The researchers comment that chemsex sessions may last several days and involve mucosally traumatic sex with multiple partners. Given the high incidence of HIV in this population, sexual partners who met at chemsex parties may be men who have very recently acquired HIV, have not been diagnosed and have an extremely high viral load.
A new diagnosis of hepatitis C occurred in 0.2% of men who did not report chemsex and 2.8% of men who did (eleven men in total). In multivariate analysis, this amounts to a ninefold increase in risk (adjusted odds ratio 9.2, 95% confidence interval 2.3-36.3).
Similarly, diagnoses of STIs were elevated in men involved in chemsex. This was true for all STIs (adjusted odds ratio 3.5), rectal STIs (4.5) and acute bacterial STIs (3.9).
Gay and bisexual men attending sexual health services should be assessed for chemsex participation, the researchers say. “Disclosure should prompt health promotion, harm minimization and wellbeing interventions.”