Post-diagnosis HCV RNA testing rates prior to HCV treatment among people living with HIV with HCV antibody positivity in the Asia-Pacific region

Abstract

HCV RNA test determines current active infection and is a requirement prior to initiating HCV treatment. We investigated trends and factors associated with post-diagnosis HCV RNA testing rates prior to HCV treatment, and risk factors for first positive HCV RNA among people living with HIV (PLHIV) with HCV in the Asia-Pacific region.

PLHIV with positive HCV antibody and in follow-up after 2010 were included. Patients were considered HCV-antibody positive if they ever tested positive for HCV antibody (HCVAb). Repeated measures Poisson regression model was used to analyse factors associated with post-diagnosis HCV RNA testing rates from positive HCVAb test. Factors associated with time to first positive HCV RNA from positive HCVAb test were analysed using Cox regression model.

There were 767 HCVAb positive participants included (87% from LMICs) of whom 11% had HCV RNA tests. With 163 HCV RNA tests post positive HCVAb test, the overall testing rate was 5.05 per 100 person-years. Factors associated with increased testing rates included later calendar years of follow-up, HIV viral load ≥ 1000 copies/mL, and higher income countries. Later calendar years of follow-up, ALT >5 times its upper limit of normal, and higher income countries were associated with shorter time to first positive HCV RNA test.

Testing patterns indicated that uptake was predominantly in high income countries possibly due to different strategies used to determine testing in LMICs. Expanding access to HCV RNA, such as through lower-cost point of care assays, will be required to achieve elimination of HCV as a public health issue.

Background

Despite advances in HIV treatments in the Asia-Pacific, over 2.2 million people living with HIV (PLHIV) remain affected. This ranks it as the region with the second-highest HIV population, following sub-Saharan Africa ¹. A major complicating factor is the widespread occurrence of hepatitis C virus (HCV) among these individuals, particularly noticeable in countries like India, Indonesia, Vietnam, South Korea, Hong Kong, Cambodia, and Thailand. Around 4-5 million of those living with HIV are also co-infected with HCV ², a situation that is particularly severe among people who inject drugs, where co-infection rates range between 75% to 99% ³. This dual infection exacerbates health issues by accelerating liver disease increasing the risk of severe complications, thereby significantly reducing survival rates.

In response to the global challenge posed by viral hepatitis, the World Health Organization (WHO) has set targets to reduce the incidence of viral hepatitis by 90% and mortality by 65%, aiming to eliminate viral hepatitis as a public health threat by 2030 ^3,4. The introduction of direct-acting antiviral agents (DAAs) and better diagnostic techniques have allowed some countries to make headway towards these goals. ^5–7 However, numerous nations, especially those in the Asia-Pacific and sub-Saharan Africa with high hepatitis C virus (HCV) burdens, struggle to provide adequate HCV care due to obstacles like insufficient laboratory infrastructure, challenges in connecting patients to care, lack of funds for HCV initiatives, and a shortage of trained medical personnel ^7–9. The high cost of HCV testing remains a significant hurdle, particularly in lower-middle income countries (LMICs), hindering progress towards achieving WHO’s objectives ^10,11.

The mangement of HCV care begins with the serological diagnosis of HCV, immediately followed by HCV nucleic acid testing (NAT) as recommended by the World Health Organization (WHO) to confirm active infection. Positive result of this test determines the appropriate course of HCV care and treatment making it a crucial test in HCV care. HCV RNA testing is also used to monitor treatment response and to confirm sustained virological response ^3,4. While such testing is routine in high-income countries, LMICs often face challenges like high costs, lack of testing facilities, and shortage of trained staff, leading to less frequent testing ¹². A study from the USA on HCV RNA testing prior to the use of DAA indicates that while access to follow-up HCV RNA testing has improved, factors such as age, gender, and socioeconomic status continue to influence the likelihood of undergoing these tests ¹³.

In LMICs, certain HCV treatment programs have adopted a targeted approach for HCV RNA testing to manage costs effectively.^14,15 This strategy prioritizes individuals who show clinical signs and symptoms of liver disease or are considered at risk for it. For example, participants with elevated levels of liver enzymes such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), receive more prompt and frequent testing compared to those with normal enzyme levels ^16,17. A study conducted in Cambodia implemented a targeted HCV testing strategy among PLHIV, developing a risk score to guide testing efforts. ¹⁴ Recognising the limitations of HCV RNA testing in LMICs, the WHO recommends the use of these strategies for such settings. ¹⁸ Although PLHIV who are considered a “targeted” population, are recommended for routine HCV screening and HCV RNA testing irrespective of other risk factors, a previous study on the HCV cascade of care among adult PLHIV within our cohort identified a low proportion of HCV RNA testing ¹⁹. This finding suggests the possible use of a targeted testing approach, where only PLHIV with high risk factors undergo HCV RNA testing, contrary to the general recommendation for testing all PLHIV. To investigate whether a targeted testing approach is being used in the region and to determine HCV RNA testing rates, we aimed to assess trends and identify factors associated with post-diagnosis HCV RNA testing rates prior to HCV treatment, and risk factors for first positive HCV RNA among PLHIV with positive HCV-antibody in the Asia-Pacific region.

Methods

The Therapeutics Research, Education, and AIDS Training in Asia (TREAT Asia) HIV Observational Database Low Intensity Transfer (TAHOD-LITE) study is a prospective observational cohort study of the International Epidemiology Databases to Evaluate AIDS Asia-Pacific consortium. TAHOD-LITE collects a limited data set on adults aged ≥18 years including patient demographics, hepatitis serology, ART history, and limited laboratory data (glucose and creatinine) from all patients who have received care at 10 participating clinical sites in Cambodia, Hong Kong SAR, India, Indonesia, South Korea, Thailand, and Vietnam. The 2019 data transfer also collected data on viral hepatitis diagnosis and treatment data to understand care practices ¹⁹. Detailed methods and data transfer processes for TAHOD-LITE have previously been described. ²⁰ Institutional Review Board approvals which included participant informed consenting if required were obtained at all participating sites, the data management and analysis centre (The Kirby Institute, University of New South Wales Sydney, Sydney, Australia) and the coordinating centre (TREAT Asia/amfAR, Bangkok, Thailand).

Participant inclusion and study endpoints

We included participants enrolled in TAHOD-LITE, who started ART (3 or more antiretrovirals), tested positive for HCV antibody (HCVAb) after 2010. HCV-antibody positivity was defined as ever testing positive for HCVAb test. In the first objective, we assessed HCV RNA testing rates after HCV diagnosis but before the initiation of HCV RNA treatment as primary endpoints. For the second objective, with the first positive HCV RNA test as the endpoint, we assessed the time to first positive HCV RNA test from HCV diagnosis. We assessed risk factors for first positive HCV RNA test for two main reasons: firstly, a positive HCV RNA test result determines active HCV infection which leads to HCV treatment; secondly, we hypothesized that a targeted testing approach for HCV RNA among PLHIV may be utilized in the region. Comparing our findings with other studies on targeted testing would allow us to determine if this strategy was used in the region.

Statistical analysis

Objective 1: Trends and factors associated with post-diagnosis HCV RNA testing rates prior to treatment

Factors associated with post-diagnosis HCV RNA testing rates prior to HCV treatment were assessed using repeated measures Poisson regression model with random effects on participant and adjusted for World Bank country income. Participants were followed from date of first positive HCVAb test and were censored at the start of HCV treatment for those who initiated treatment, or date of their last clinic visit, date of death, date transferred out, or date lost-to follow-up (LTFU) whichever occurred first. LTFU was defined as no clinic visit in the past 12 months from the time of last patient contact. Incidence rates of HCV RNA testing were plotted over calendar year of follow-up from 2010 to 2018.

Objective 2: Risk factors for first positive HCV RNA test

Cox regression model adjusted for World Bank country income was used to assess factors associated with time to first positive HCV RNA from HCVAb positive test. For this analysis, participants were followed from the date of their positive HCVAb test until their first positive HCV RNA test. Those who did not have a positive HCV RNA test or did not have a HCV RNA test had their risk time end on the date of their last clinic visit, date of death, date transferred out, or date lost-to follow-up (LTFU) whichever occurred first.

Covariates included

Fixed covariates included in both analyses were age, sex, HIV exposure category, HBV co-infection status, initial ART regimen, and World Bank country income level. Patients were determined as positive for HBV co-infection if they ever tested positive for HBV surface antigen test. Time varying covariates included were calendar year of follow-up, CD4 cell count, HIV RNA, fasting blood glucose, ALT, AST, and platelet measurements. Calendar year of follow-up was categorized into three periods: 2010-2012, representing the time prior to the introduction of DAAs; 2013-2015, during the inception of DAAs; and 2016-2018, when WHO put forward the strategy to eliminate HCV as a public threat. High fasting blood glucose was defined as a single fasting blood glucose measurement ≥ 7 mmol/L. Laboratory measures that produce Grade 3 or higher levels of adverse events as determined by Division of AIDS (DAIDS) Table for Grading the Severity of Adult and Pediatric Adverse Events, (DAIDS ) were used to determine high or low cut-offs. High ALT and AST were defined as ALT >5 times its upper limit of normal (ULN) and AST > 5 x ULN. Low platelets counts were defined as platelets <50 cells/L ²¹.

All data management and statistical analyses were performed using SAS software version 9.4 (SAS Institute Inc., Cary, NC, USA) and Stata software version 16.1 (StataCorp, College Station, TX, USA).

Results

A total of 767 adult participants with HIV were included in the analysis who were HCVAb positive and on ART with follow-up data from 2010 – 2018. Most were male (82%), and from LMICs (87%). Their most common mode of HIV exposure was through injecting drug use (48%). At ART initiation, the median age was 33 years (IQR 29-39), median HIV viral load was 180,000 copies/mL (IQR 37,600-470,000), and median CD4 count was 132 cells/μL (IQR 31-291) with 92% on a nucleoside reverse transcriptase inhibitor (NRTI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) ART regimen.

During the follow-up period, 11% (83/767) had at least one post-diagnosis HCV RNA test. Similar to the total population, majority (72%) were male and largely from LMICs (63%). At ART initiation, the median age was 35 years (IQR 31-43), median HIV viral load was 190,000 copies/mL (IQR 25,514-430,000), and median CD4 count was 251 cells/μL (IQR 67-439) with most (78%) on a NRTI and NNRTI regimen. Their mode of HIV exposure was most commonly through heterosexual contact (49%) (Table 1).

Table 1.

Participant demographics information at ART start

	Total patients diagnosed anti-HCV positive (%)	Patients with post-diagnosis HCV RNA testing (%)	Participants without post-diagnosis HCV RNA testing (%)
	N= 767 (100)	N= 83 (11)	N=684 (89)	p-value
Age at ART initiation (years)
Median (IQR)	33 (29 - 39)	35 (31-43)	33 (29-39)	0.078
≤30	238 (31)	19 (23)	219 (32)	0.190
31-40	376 (49)	42 (51)	334 (49)
41-50	114 (15)	15 (18)	99 (15)
>50	39 (5)	7 (8)	32 (5)
Sex
Male	632 (82)	63 (76)	569 (83)	0.100
Female	135 (18)	20 (24)	115 (17)
Mode of HIV Exposure
Heterosexual contact	304 (39)	41 (49)	263 (39)	<0.001
MSM	56 (7)	17 (20)	39 (6)
Injecting drug use	365 (48)	20 (24)	345 (50)
Other/unknown	42 (6)	5 (6)	37 (5)
Pre-ART viral load (copies/mL)
Median (IQR)	180000 (37600-470000)	190000 (25514-430000)	169500 (36365-460500)	0.67
<1000	11 (1)	2 (2)	9 (1)	<0.001
≥1000	211 (28)	44 (53)	167 (24)
Not reported	545 (71)	37 (45)	508 (74)
Pre-ART CD4 (cells/μL)
Median (IQR)	132 (31 - 291)	251 (67-439)	113(33-273)	0.089
≤200	236 (31)	34 (46)	202 (29)	<0.001
201-350	88 (11)	18 (22)	70 (10)
351-500	37 (5)	11 (13)	26 (4)
>500	23 (3)	7 (8)	16 (2)
Not reported	383 (50)	13 (16)	370 (54)
Hepatitis B co-infection
Negative	624 (81)	64 (77)	560 (82)	0.002
Positive	91 (12)	6 (7)	85 (12)
Not reported	52 (7)	13 (16)	39 (6)
High fasting blood glucose
No (< 7 mmol/L)	236 (31)	47 (57)	189 (28)	<0.001
Yes (≥ 7 mmol/L)	19 (2)	2 (2)	17 (3)
Not reported	512 (67)	34 (41)	478 (70)
ALT
≤5xULN	130 (17)	29 (35)	101 (15)	<0.001
>5xULN	2 (0)	1(1)	1 (0)
Not reported	635 (83)	53 (64)	582 (85)
AST
≤5xULN	89 (12)	18 (22)	71 (10)	0.009
>5xULN	1 (0)	0 (0)	1 ( 0)
Not reported	677 (88)	65 (78)	612 (90)
Platelets
<50	5 (1)	1 (1)	4 (1)	<0.001
≥50	106 (14)	24 (29)	82 (12)
Not reported	656 (86)	58 (70)	598 (87)
Initial ART Regimen
NRTI+NNRTI	708 (92)	65 (78)	643 (94)	<0.001
NRTI+PI	31 (4)	11 (13)	20 (3)
Other	28 (4)	7 (8)	21 (3)
Country Income Level
Lower Middle	665 (87)	52 (63)	613 (90)	<0.001
Upper Middle	32 (4)	4 (5)	28 (4)
High	70 (9)	27 (33)	43 (6)

TAHOD-LITE, TREAT Asia HIV Observational Database-Low Intensity TransfEr; No., number; HCV RNA,; HCV, hepatitis C virus; ART, Antiretroviral Therapy; IQR, interquartile range; MSM, Men who have sex with men; ALT, alanine aminotransferase; AST, aspartate aminotransferase; NRTI, Nucleoside Reverse Transcriptase Inhibitor; NNRTI, Non-nucleoside reverse transcriptase inhibitor; PI, Protease Inhibitor;

^‡ART start is defined as the date patients started their first triple regimen.

^*Comparison of those with and without test: p-value for Chi-square test has been provided for categorical variables and p-value for Wilcoxon Rank Sum Test has been provided for the continuous variables.

Among the 83 participants who underwent post diagnosis HCV RNA testing and subsequently received HCV treatment, 55% had only one HCV RNA test. Notably, 93% of these participants were from LMICs (93%). In contrast, participants who received more than one HCV RNA test (46% of 83) were predominantly from high income countries (65%) (Supplementary table A). Furthermore, positive HCV RNA tests were found among 93% of those who had post-diagnosis HCV RNA test. Characteristics of those who had a negative test and always had positive test are shown in supplementary table B. In terms of treatment, the majority (72% of 83) initiated therapy with direct-acting antivirals (DAAs), utilizing combinations such as Daclatasvir/Sofosbuvir and Sofosbuvir/Ledipasvir. Additionally, 19% of the participants were treated with a regimen that combined DAAs and interferons, while the remaining 8% received treatments based solely on interferons.

Between 2010 – 2018, there were 163 HCV RNA tests post HCV diagnosis from 83 participants, giving an overall crude testing rate of 5.05 per 100 person-years (100PYs) for the total study population. An increase in HCV RNA testing rate was observed from 4.23/100PYS in 2010 to almost 7.98/100PYS in 2018 (Figure 1).

Figure 1:

Trends in post-diagnosis HCV RNA testing show an increase in testing rate from 4.23/100PYS in 2010 to almost 7.98/100PYS in 2018

Factors associated with higher post-diagnosis HCV RNA testing rates were later calendar years of follow-up (2016-2019: IRR 2.49; 95% CI 1.19-5.22, p=0.015) compared to 2010-2012, HIV viral load ≥ 1000 copies/mL (IRR 4.31, 95% CI 2.51-7.39, p<0.001) compared to those with HIV viral load < 1000 copies/mL, and those in higher income countries (high: IRR 17.91; 95% CI 6.92-46.32, p<0.001; upper-middle: IRR 4.94; 95% CI 1.59-15.38, p=0.006) compared to lower-middle income settings. Decreased testing rates were seen among those whose HIV mode of exposure was by injecting drug use (IRR 0.29, 95% CI 0.15-0.55, p<0.001) compared to those whose mode of HIV exposure was via heterosexual contact (Table 2).

Table 2:

Factors associated with post-diagnosis HCV RNA testing rates

					Univariate			Multivariate
	Total patients	Follow-up (years)	Number of HCV RNA tests	aCrude rate	IRR	95% CI	p-value	IRR	95% CI	p-value
Total	767	3226.3	163	5.05
* Calendar year							0.004			<0.001
2010 – 2012	~	511.35	12	2.35	1			1
2013 – 2015	~	1423.83	55	3.86	1.1	(0.55, 2.20)	0.781	1.17	(0.57, 2.42)	0.665
2016 – 2018		1291.14	96	7.44	1.97	(1.00, 3.91)	0.051	2.49	(1.19, 5.22)	0.015
Age at ART initiation (years)							0.416
≤ 30	238	1027.6	49	4.77	1
31-40	376	1619.47	61	3.77	1.52	(0.78, 2.95)	0.214
41-50	114	439.14	34	7.74	1.84	(0.81, 4.18)	0.146
51+	39	140.1	19	13.56	1.94	(0.53, 7.13)	0.317
Sex
Male	632	2692.8	127	4.72	1
Female	135	533.52	36	6.75	1.78	(0.88, 3.62)	0.109
Mode of HIV Exposure							0.003			0.002
Heterosexual contact	304	1248.56	69	5.53	1			1
MSM	56	163.97	59	35.98	0.79	(0.28, 2.26)	0.661	0.86	(0.30, 2.43)	0.771
Injecting drug use	365	1677.95	24	1.43	0.3	(0.16, 0.58)	<0.001	0.29	(0.15, 0.55)	<0.001
Other/unknown	42	135.83	11	8.1	0.43	(0.12, 1.62)	0.214	0.52	(0.14, 1.94)	0.333
* Viral Load (copies/mL)
<1000	~	939.48	76	8.09	1			1
≥ 1000	~	249.75	29	11.61	2.77	(1.66, 4.61)	<0.001	4.31	(2.51, 7.39)	<0.001
Not reported	~	2037.09	58	2.85
* CD4 (cells/μL)							0.919
≤ 200	~	352.4	18	5.11	1
201-350	~	397.06	15	3.78	0.43	(0.19, 0.96)	0.039
351-500	~	355.67	29	8.15	0.76	(0.36, 1.59)	0.464
> 500	~	421.41	46	10.92	0.63	(0.30, 1.31)	0.217
Not reported	~	1699.78	55	3.24
Hepatitis B co-infection
Negative	624	2701.11	123	4.55	1
Positive	91	414.24	19	4.59	0.75	(0.30, 1.84)	0.526
Not reported	52	110.96	21	18.93
High fasting blood glucose
No (< 7 mmol/L)	~	1266.91	93	7.34	1
Yes (≥ 7 mmol/L)	~	80.68	5	6.2	1.29	(0.37, 4.45)	0.692
Not reported	~	1878.73	65	3.46
* ALT
≤ 5 x ULN	~	833.57	72	8.64	1
> 5 x ULN	~	20.05	11	54.87	1.84	(0.82, 4.14)	0.139
Not reported	~	2372.7	80	3.37
* AST
≤ 5 x ULN	~	742.38	49	6.6	1
> 5 x ULN	~	18.67	4	21.43	2.42	(0.67, 8.72)	0.178
Not reported	~	2465.27	110	4.46
* Platelets
< 50	~	13.44	3	22.33	1
≥ 50	~	781.23	75	9.6	0.3	(0.05, 1.89)	0.2
Not reported	~	2431.65	85	3.5
Initial ART Regimen							0.834
NRTI+NNRTI	708	3087.15	103	3.34	1
NRTI+PI	31	80.02	31	38.74	1.39	(0.42, 4.58)	0.588
Other	28	59.14	29	49.04	0.95	(0.28, 3.18)	0.928
World Bank Country Income							<0.001			<0.001
Lower Middle	665	2911.09	61	2.1	1			1
Upper Middle	32	144.41	15	10.39	5.95	(2.14, 16.53)	0.001	4.94	(1.59, 15.38)	0.006
High	70	170.82	87	50.93	25.42	(13.23, 48.82)	<0.001	17.91	(6.92, 46.32)	<0.001

No., number; HCV RNA,; HCV, hepatitis C virus; ART, Antiretroviral Therapy; MSM, Men who have sex with men; ALT, alanine aminotransferase; AST, aspartate aminotransferase; NRTI, Nucleoside Reverse Transcriptase Inhibitor; NNRTI, Non-nucleoside reverse transcriptase inhibitor; PI, Protease Inhibitor; IRR, Incidence rate ratio

^a-crude rate, per 100 person-years

^*time-updated variables

Not reported values were included in the analysis as a separate category but were excluded from test for heterogeneity. Covariates with p<0.10 in the univariate analysis (highlighted in bold) were fitted into the multivariate model. Backward-stepwise selection process was used, and covariates with p<0·05 were considered statistically significant (highlighted in bold) and retained in the multivariate model

Among the 163 post-diagnosis HCV RNA tests, 94% (153) were positive tests. First positive HCV RNA tests were found among 9% (66) participants with follow-up. Factors associated with shorter time to first positive HCV RNA test were later calendar years of follow-up (2016-2019: HR 4.68; 95% CI 1.53-14.30, p=0.007; 2013-2015: HR 3.85; 95% CI 1.33-11.17, p=0.013 ) compared to 2010-2012, ALT >5.0 times ULN (HR 3.65, 95% CI 1.25-10.68, p=0.008), and high-income countries (high: HR 7.39; 95% CI 3.65-14.94, p<0.001) compared to lower-middle income settings (Table 3).

Table 3:

Factors associated with time to first positive post-diagnosis HCV RNA test

					Univariate			Multivariate
	No. patients	Follow up (years)	No. of first positive HCV RNA test	aCrude rate	HR	95% CI	p-value	HR	95% CI	p-value
Total	745	2918.27	66	2.26
* Calendar year							0.004			0.007
2010 - 2012	~	333.34	4	1.2	1			1
2013 - 2015	~	1304.82	28	2.15	3.79	(1.31, 10.97)	0.014	3.85	(1.33, 11.17)	0.013
2016 - 2018	~	1280.1	34	2.66	5.09	(1.67, 15.52)	0.004	4.68	(1.53, 14.30)	0.007
Age at cART initiation (years)							0.209
≤30	229	912.16	15	1.64	1
31-40	367	1474.32	35	2.37	1.73	(0.94, 3.18)	0.078
41-50	110	411.29	13	3.16	1.89	(0.90, 3.97)	0.094
51+	39	120.5	3	2.49	0.91	(0.26, 3.16)	0.884
Sex
Male	612	2418.26	53	2.19	1
Female	133	500	13	2.6	1.34	(0.73, 2.48)	0.347
Mode of HIV Exposure							0.336
Heterosexual contact	299	1173.73	26	2.22	1
MSM	56	117.1	17	14.520	1.2	(0.55, 2.62)	0.644
Injecting drug use	349	1487.73	19	1.28	0.65	(0.36, 1.19)	0.164
Other/unknown	41	139.71	4	2.86	0.63	(0.21, 1.91)	0.417
* Viral Load (copies/mL)
<1000	~	910.35	34	3.73	1
≥1000	~	234.190	23	9.82	1.63	(0.88, 3.03)	0.123
Not reported	~	1773.72	9	0.51
* CD4 (cells/μL)							0.417
≤200	~	352.18	17	4.83	1
201-350	~	394.24	9	2.28	0.56	(0.24, 1.29)	0.172
351-500	~	357.35	13	3.64	0.93	(0.43, 2.03)	0.865
>500	~	415.73	21	5.05	1.09	(0.52, 2.26)	0.823
Not reported	~	1398.77	6	0.43
Hepatitis B co-infection
Negative	604	2460.68	57	2.32	1
Positive	89	360.76	6	1.66	0.63	(0.27, 1.47)	0.282
Not reported	52	96.82	3	3.10
High fasting blood glucose
No (< 7 mmol/L)	~	1230.87	49	3.98	1
Yes (≥ 7 mmol/L)	~	74.46	3	4.03	1.16	(0.36, 3.76)	0.803
Not reported	~	1612.94	14	0.87
* ALT
≤ 5 x ULN	~	839.07	33	3.93	1			1
> 5 x ULN	~	16.49	4	24.25	4.39	(1.51, 12.75)	0.007	3.65	(1.25, 10.68)	0.008
Not reported	~	2062.7	29	1.41
* AST
≤ 5 x ULN	~	727.09	19	2.61	1
> 5 x ULN	~	18.55	2	10.78	4.39	(0.96, 19.99)	0.056
Not reported	~	2172.63	45	2.07
* Platelets
< 50	~	12.77	1	7.83	1
≥ 50	~	781.45	32	4.09	0.48	(0.06, 3.56)	0.472
Not reported	~	2124.05	33	1.55
Initial ART Regimen							0.950
NRTI+NNRTI	686	2820	50	1.77	0.95
NRTI+PI	31	61.66	9	14.6	1.02	(0.43, 2.43)	0.963
Other	28	36.61	7	19.12	0.88	(0.34, 2.26)	0.787
World Bank Country Income							<0.001			<0.001
Lower Middle	643	2691.52	37	1.37	1			1
Upper Middle	32	118.51	4	3.38	2.26	(0.81, 6.36)	0.121	1.49	(0.49, 4.50)	0.477
High	70	108.23	25	23.1	12.22	(7.23, 20.64)	<0.001	7.39	(3.65, 14.94)	<0.001

No., number; HCV RNA,; HCV, hepatitis C virus; ART, Antiretroviral Therapy; MSM, Men who have sex with men; ALT, alanine aminotransferase; AST, aspartate aminotransferase; NRTI, Nucleoside Reverse Transcriptase Inhibitor; NNRTI, Non-nucleoside reverse transcriptase inhibitor; PI, Protease Inhibitor; HR, Hazard ratio

^a-crude rate, per 100 person-years

^*time-updated variables

Not reported values were included in the analysis as a separate category but were excluded from test for heterogeneity. Covariates with p<0.10 in the univariate analysis (highlighted in bold) were fitted into the multivariate model. Backward-stepwise selection process was used, and covariates with p<0·05 were considered statistically significant (highlighted in bold) and retained in the multivariate model

Discussion

Among 767 HIV participants on ART with HCV antibody positivity after 2010, our study found a post-diagnosis HCV RNA testing rate of 5.05/100PY. The overall trends in HCV RNA testing demonstrated an increase in testing rates over the years. Increased testing rates were found in later calendar years of follow-up, those with HIV viral load ≥ 1000 copies/mL, and among those from high-income countries. Time to first positive HCV RNA test occurred sooner in later calendar years of follow-up, those with ALT >5 x ULN, and in higher income countries.

Studies with focus on HCV RNA testing in LMICs were limited, therefore, we were unable to compare the post-diagnosis HCV RNA testing rates across similar settings. However, guidelines on HCV treatment and testing recommend a single HCV RNA test following positive HCV diagnosis to confirm active infection and testing for all PLHIV with positive HCV antibody ^3,4. Given that only 83 of our participants had post-diagnosis HCV RNA tests, it suggests that HCV RNA testing rates in our region remains below the recommended levels. A possible explanation for the low testing rates is due to clinical practices that vary by country, particularly influenced by local resources and economic constraints. While most clinical sites attempt to follow the globally recommend testing guidelines, some countries may opt for alternative strategies or methods such as monitoring liver enzymes or using HCV core antigen (HCVcAg) tests as surrogates for HCV RNA testing. These alternatives are often chosen due to the high costs associated with HCV RNA tests, limited availability of necessary laboratory equipment, or a shortage of qualified personnel to conduct these tests. Although our data does not explicitly confirm the use of different testing strategies within our cohort, adjusting our analyses for the country’s income level has revealed significant differences in testing rates, suggesting that economic factors play a critical role in HCV RNA testing rates.

While an overall low testing rate was observed, our study did find an increasing trend in post-diagnosis HCV RNA testing prior to treatment over the years. Although we were not able to compare these results specifically to HCV RNA testing, similar trends were identified in studies examining HCV testing rates which included both HCV diagnostic tests and NATs. For example, studies on PLHIV in Australian cohorts found 67% increase in testing rates (17.1 to 51.4 tests per 100 patients) from 2007 to 2015 ²². Furthermore, there was a 35% increase in HCV testing between pre-DAA (2013-2015) and post-DAA (2016-2018) ²³.

Our study found increased rate of testing frequency and shorter time interval leading to the first positive HCV RNA test occurring in later calendar years of follow-up. These findings align with results from other studies that have found DAA use to be associated with increased HCV RNA tests ^10,23,24. By 2015, most countries including LMICs had transitioned to use DAAs from interferons for HCV treatment. With shorter treatment durations and improving cure rates resulting from the adoption of DAAs for treatment, there was a need to increase testing to link HCV patients to care ^{2,10,19,25,26}. Continuous assessment of HCV cascades of care prompted for strategies to reduce gaps in HCV care. These strategies included decentralised testing and community-based approach to testing ^9,27–31. The introduction of rapid diagnostic test kits and point-of-care testing represent more recent changes brought forward to facilitate faster testing and improve linkage to care, with the overall aim of reaching the 2030 global targets. Some of our clinical sites may have implemented these strategies to a certain level within their HCV programs and this may explain the improved testing rates and shorter time intervals leading to the first positive HCV RNA test in later calendar years. Further strategies to make cost-effective testing methods readily available are required to further improve testing rates.

Our study found an increased rate of testing among individuals with HIV viral load ≥ 1000 copies/mL. Despite the small proportion of post-diagnosis HCV RNA testing, this finding may be attributed to clinical practices where clinicians, being aware of their patients’ behaviours, recommend those with HIV infection for active HCV infection testing. It is also possible that these participants present themselves for care very late, and thus are recommended for HCV RNA testing immediately following a positive HCV diagnosis. We also observed a shorter time interval leading to the first positive HCV RNA test among those with ALT levels ≥ 5 x ULN. These findings are consistent with finding in existing literature on targeted testing approaches. The study on targeted testing for HCV among PLHIV in Cambodia found that individuals with higher HIV viral load were tested more frequently to expedite linkage to HCV care. Similarly, those with elevated ALT levels were among the predictors used to determine the need for targeted testing of HCV infection ¹⁶. Our findings suggest that a similar targeted testing approach may be adopted in our region. While this emphasises the feasibility of a targeted testing approach for HCV RNA testing within the Asia-Pacific region, it also highlights the fact that this test is expensive. Substantial changes are required to make this test more affordable, especially if a universal testing approach is to be considered to improve testing rates.

High-income countries were found to have increased rate of testing frequency and shorter time interval leading to the first positive HCV RNA test compared to LMICs. It is highly likely that HCV programs in high-income countries have more funding, better linked HIV-HCV care, and have increased accessibility to cost-effective testing and treatment options. For example, there have been suggestions to use alternative tests, such as the use of less expensive serological testing of HCVcAg as a substitute for HCV RNA testing. However, not all LMIC have access to these alternative tests ^7,32. Additionally, in many LMIC, HCV RNA tests are not fully subsidized. With the cost of a single test ranging from USD $20 to $200, this expense is out of reach for the majority of patients in resource-limited settings ^8,33. Modelling studies have identified that an amount of less than USD $5 for a single test would enable LMICs to reach the elimination targets ¹². Our study results highlight the need for more comprehensive attention and investment in HCV programs for PLHIV in LMICs to align these countries with globally recommended HCV testing and care standards.

Limitations

Several limitations were identified in our study. Lack of linkage between some clinics in our cohort and the laboratories where HCV RNA tests are analysed, can cause for delays in test results to reach the clinics. As a result, there is a possibility that the HCV RNA testing rates observed in this study were underestimated. Additionally, there was limited literature available on HCV RNA testing rates in other settings. Therefore, we compared our findings primarily to the testing recommendations outlined in the WHO guidelines, rather than across different clinical settings within the Asia-Pacific region.

Conclusion

Higher post-diagnosis HCV RNA testing rates prior to HCV treatment and shorter time to first positive HCV RNA were observed in more recent calendar years and in higher income countries, indicating poor accessibility to HCV RNA testing in LMICs, with a possible targeted testing approach in this setting. Additional resources, such as affordable point-of-care HCV RNA tests, should be made more readily available in LMICs in order to facilitate the elimination of HCV as a public health issue by 2030.

Data availability statement

As part of Ethics agreements, data are not available publicly.