Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 https://doi.org/10.1186/s12879-022-07352-z RESEARCH ARTICLE Open Access Low CD4/CD8 ratio is associated with increased morbidity and mortality in late and non‑late presenters: results from a multicentre cohort study, 2004–2018 Lourdes Domínguez‑Domínguez1†, Marta Rava2,3*† , Otilia Bisbal1,3, Luis Lopez‑Cortés3,4, Joaquín Portilla5, Daniel Podzamczer6, Julián Olalla7, Daniel Fuster8, Rafael Rubio1,3, Inmaculada Jarrín2,3, José Antonio Iribarren9†, Santiago Moreno3,10† and Cohort of the Spanish HIV/AIDS Research Network (CoRIS) Abstract Background: To study whether the association between the CD4/CD8 ratio variation over time and the develop‑ ment of clinical outcomes vary in late presenters (CD4 count < 350/µL or AIDS event at enrolment) or advanced presenters (CD4 count < 200/µL or AIDS event at enrolment). Methods: We included ART-naïve adults from the Cohort of the Spanish HIV/AIDS Research Network (CoRIS) enrolled between January 2004 up to November 2018 and with at least 6 months of follow-up. We used extended Cox pro‑ portional hazard models to estimate the hazard ratios (HRs) for the association between CD4/CD8 ratio over time and a composite endpoint of the occurrence of the first AIDS event, first serious non-AIDS event or overall mortality occurring from 6 months after enrolment. HRs in non-late, late and advanced presenters were obtained by including an interaction term between late presentation status and CD4/CD8 ratio over time. Results: Of 10,018 participants, 55.6% were late presenters and 26.5% were advanced presenters. Compared with CD4/CD8 ratio > 0.4, CD4/CD8 ratio ≤ 0.4 over time was associated with an increased risk of experiencing the compos‑ ite endpoint in non-late (HR 1.90; 95%CI 1.48, 2.43), late (HR 1.94; 1.46, 2.57) and advanced presenters (HR 1.72; 1.26, 2.34). Similarly, CD4/CD8 ratio ≤ 0.4 over time was associated with a higher risk of developing an AIDS event (HR 3.31; 2.23, 4.93 in non-late; HR 2.75; 1.78, 4.27 in late and HR 2.25; 1.34, 3.76 in advanced presenters) or serious non-AIDS event (HR 1.39; 0.96, 2.02 in non-late, HR 1.62; 1.10, 2.40 in late and HR 1.49; 0.97, 2.29 in advanced presenters) as well as with a higher risk of overall mortality (HR 1.49; 0.92, 2.41 in non-late, HR 1.80; 1.04, 3.11 in late and HR 1.61; 0.92, 2.83 in advanced presenters) compared to CD4/CD8 > 0.4, regardless of the late presentation status. Conclusions: A low CD4/CD8 measured over time is associated with increased risk of morbidity and mortality in people living with HIV independently of their late presentation status. These data support the prognostic role of CD4/ CD8 over time and can help defining a subgroup of patients who need closer monitoring to avoid comorbidities. *Correspondence: mrava@isciii.es † Lourdes Domínguez-Domínguez, Marta Rava, José Antonio Iribarren, and Santiago Moreno have equal contributions. 2 Centro Nacional de Epidemiología, Instituto de Salud Carlos III, Avda. Monforte de Lemos 5, 28029 Madrid, Spain Full list of author information is available at the end of the article © The Author(s) 2022. 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The Creative Commons Public Domain Dedication waiver (http://​creat​iveco​ mmons.​org/​publi​cdoma​in/​zero/1.​0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 Page 2 of 10 Keywords: Late presentation, CD4/CD8, Clinical outcomes, AIDS events, Serious non-AIDS events, Mortality Background Definitions of late presentation Mortality in people living with HIV (PLWH) has Late presenters were participants with CD4 count below decreased since the advent of highly active antiretrovi- 350/µL and/or with an AIDS event occurred before ral treatment (ART) [1]. Nonetheless comorbidities are the 24th week after enrolment regardless of the CD4 increasing [2, 3] and they are particularly high in those cell count, both conditions met before ART initiation. who present late for diagnosis [4, 5]. Advanced presenters were participants with CD4 count In this scenario, efforts have been made to find prog- below 200/µL and/or with an AIDS event occurred nostic markers of clinical events [6]. The CD4+ T cells/ before the 24th week after enrolment regardless of the CD8+ T cells ratio (CD4/CD8 ratio) has shown an CD4 cell count, both conditions met before ART initia- association with both AIDS and non-AIDS events in tion [12]. By definition, all advanced presenters were also virologically suppressed individuals [7]. Particularly, a late presenters. We considered as non-late presenters CD4/CD8 ratio ≤ 0.4 has been found to be associated participants with CD4 count greater than 350/µL and no with T cell activation, innate immune activation and AIDS events. an immunosenescent phenotype, and to predict seri- ous non-AIDS events [8, 9], even in virologically sup- pressed persons with absolute CD4 count > 500/µL. Health outcomes Although mortality and morbidity are especially high The primary endpoint was clinical progression, defined in late presenters [4, 10] the potential prognostic role as a composite endpoint of the occurrence of the first of the CD4/CD8 ratio has not been studied yet in this AIDS or serious non-AIDS event or death from any population. Our aim is to evaluate whether the varia- cause occurred from 6 months after enrolment. As seri- tion in CD4/CD8 ratio over time is associated with ous non-AIDS event we considered any of the following the development of AIDS and non-AIDS events and conditions: cardiovascular events (myocardial infarction, mortality in participants from the cohort of the Span- angina, heart disease, transient ischemic attack, revers- ish HIV/AIDS Research Network (CoRIS) and to study ible ischemic deficit, stroke and peripheral arteriopathy whether these associations vary with late presentation or death from cardiovascular disease), renal events (end- and advanced disease. stage renal disease, initiation of dialysis or renal trans- plantation, or death from renal disease), liver events (ascites, digestive haemorrhage due to oesophageal Methods varices, hepatic encephalopathy, liver transplantation, Study design or death from liver disease), non-AIDS malignancy or CoRIS is an open, prospective multicentre cohort death from non-AIDS malignancy, and infectious-related of persons with confirmed HIV infection, naïve to deaths. ART at study entry, recruited in 46 centres from 13 Autonomous Regions in Spain from 2004-onwards, as described in detail in [11]. CoRIS Study Groups are Statistical methods listed in Additional file 1. We classified the participants as having low (≤ 0.4) or high (> 0.4) CD4/CD8 ratio: the cut-off at 0.4 correspond to the first quartile of the overtime distribution of CD4/ Study population CD8 ratio and was chosen based on its association with We included CoRIS participants recruited from Janu- serious non-AIDS events [8]. Since both the CD4 and the ary 2004 to November 2018, age ≥ 18 years, with avail- CD8 count and their ratio vary over time and its variation able information on late presentation at enrolment, at may affect the risk of developing a clinical outcome, we least 6 months of follow up, at least one determination modelled the CD4/CD8 ratio as a time-varying covari- of CD4 count and CD8 count from the 6th month after ate. We estimated the hazard ratios (HRs) and 95% con- enrolment, and information on the clinical outcomes of fidence intervals (CI) for the association with the clinical the composite endpoint. Individuals who were moni- outcomes with extended Cox proportional hazard mod- tored in the three centres not providing data on non- els [13]. AIDS events were excluded. Briefly, the follow-up period for each person was bro- ken up into subintervals, corresponding to the CD4 and CD8 measurements. The time-varying covariates Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 Page 3 of 10 values and the endpoint were updated at each subinter- Africa or Latin America, and to have enrolled at an older val up to the occurrence of the first event or the cen- age and with a higher viral load (Table 1). soring time. We performed two sets of analysis: one set including non-late and late presenters and another one Dynamic of CD4/CD8 ratio by late presentation status including non-late and advanced presenters. To evalu- Median CD4/CD8 ratio and CD4 count increased over ate whether the association between the CD4/CD8 time in the three groups. While non-late presenters had ratio and the clinical outcomes varied with the late a median CD4/CD8 ratio above the threshold of 0.4 from presentation status, we included an interaction term 6 months after enrolment, late presenters reached it after between late presentation and over time CD4/CD8 12 months and advanced presenters after 24 months ratio in the multivariable Cox models, which allowed us (Fig. 1A, B). to obtain HRs for the association of interest in non-late The percentage of individuals with CD4/CD8 ≤ 0.4 was presenters, late presenters and advanced presenters. lower in non-late presenters than in late and advanced Multivariable models were adjusted for age presenters during the entire follow-up. More than half (< 50, ≥ 50 years) and CD4 count (< 500, ≥ 500/µL), of the individuals with late presentation or advanced that were both modelled as time-varying covariates, disease had CD4/CD8 ratio ≤ 0.4 at enrolment and over a combined variable of gender and HIV transmission time, with the highest proportion observed in advanced category (men who have sex with men, injection drug presenters (Fig. 2). use, heterosexual women, heterosexual men, other/ unknown), educational level (no education or pri- mary education alone, secondary education, university, Impact of dynamic of CD4/CD8 ratio on clinical outcomes other/unknown), region of origin (Europe, Sub-Saharan (overall and by late presentation status) Africa, Latin America, other/unknown) and presence of Regardless of their late presentation status at enrolment, hepatitis C virus antibodies (no, yes or unknown), pres- low CD4/CD8 ratio over time was associated with an ence of hepatitis B surface antigen (no, yes or unknown) increased incidence of the composite endpoint and of and viral load (< 10,000, 10,000–100,000, ≥ 100,000 each of its components (Fig. 3). copies/mL, unknown) at enrolment. As shown in Table 2, compared with CD4/CD8 All statistical analyses were performed using R ver- ratio > 0.4, CD4/CD8 ratio ≤ 0.4 was associated with an sion 4.0 [14] and extended Cox regression models were increased risk of clinical progression in non-late (HR estimated with the survival package [13, 15]. 1.90; 95%CI 1.48, 2.43), late (HR 1.94; 95%CI 1.46, 2.57), and advanced presenters (HR 1.72; 95%CI 1.26, 2.34). In general, after adjustment for a wide range of covariates Sensitivity analyses that included the CD4 count measured over time, the To account for the role of viral suppression (viral load adjusted HRs were attenuated compared with the unad- < 50 copies mL) in the association between the CD4/ justed estimates. CD8 ratio and the clinical outcomes, we included the The risk of developing an AIDS event was three times viral load as a time-varying variable (< 50, ≥ 50 cop- higher for individuals with CD4/CD8 ratio ≤ 0.4 com- ies/mL). Further, in order to evaluate whether early pared to those with CD4/CD8 ratio > 0.4 among non-late ART initiation modify the associations under study, presenters and twice as high in both late and advanced we repeated the analyses after stratification for tim- presenters. The adjusted HRs for serious non-AIDS ing of ART initiation (< 1 year vs ≥ 1 year after the events, comparing CD4/CD8 ratio ≤ 0.4 versus CD4/CD8 enrolment). ratio > 0.4, varied from 1.39 (95%CI 0.96, 2.02) in non-late to 1.62 (95%CI 1.10, 2.40) in late, and 1.49 (95%CI 0.97, 2.29) in advanced presenters. These estimates suggested Results that CD4/CD8 ratio ≤ 0.4 could be associated with seri- During the study period, 10,018 participants met the ous non-AIDS events. However, in non-late presenters inclusion criteria. Out of them, 5574 (55.6%) were non- as well as in advanced presenters, possible HRs that are late presenters, 4444 (44.4%) were late presenters and highly compatible with our data, given our model, ranged 2659 (26.5%) were advanced presenters (Table 1). from 0.96 and 0.97 (essentially no association) to 2.02 and Late presenters and advanced presenters were more 2.29 (a relatively strong association). Similar considera- likely than non-late presenters to have acquired HIV tions can also be extrapolated from the results on specific infection through heterosexual contact or injections, to serious non-AIDS events. have a lower level of education, to be from sub-Saharan Mortality associated with CD4/CD8 ratio ≤ 0.4 was 49% higher in non-late, 80% higher in late and 61% higher Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 Page 4 of 10 Table 1 Characteristics at enrolment of non-late presenters, late presenters and advanced presenters All participants, Non-late presenters, Late presenters, Advanced presenters, n = 10,018 n = 5574, 55.6% n = 4444, 44.4% n = 2659, 26.5% Age (years) Median (1st, 3rd quartile) 35.5 (29.1 43.1) 33. 4 (27.7 40.4) 38.6 (31.4 46.1) 40.2 (33.4 47.6) < 30 2469 (24.6%) 1696 (30.4%) 773 (17.4%) 327 (12.3%) 30–49 6290 (62.8%) 3422 (61.4%) 2868 (64.5%) 1742 (65.5%) ≥ 50 1259 (12.6%) 456 (8.2%) 803 (18.1%) 590 (22.2%) Transmission group (n (%)) MSM 6071 (60.6%) 3910 (70.1%) 2161 (48.6%) 1120 (42.1%) IDU 707 (7.1%) 280 (5.0%) 427 (9.6%) 295 (11.1%) Heterosexual women 1334 (13.3%) 616 (11.1%) 718 (16.2%) 451 (17.0%) Heterosexual men 1560 (15.6%) 633 (11.4%) 927 (20.9%) 645 (24.3%) Other/unknown 346 (3.5%) 135 (2.4%) 211 (4.7%) 148 (5.6%) Educational level (n (%)) Primary education or less 1390 (13.9%) 574 (10.3%) 816 (18.4%) 546 (20.5%) Secondary education 4598 (45.9%) 2648 (47.5%) 1950 (43.9%) 1185 (44.6%) University 2395 (23.9%) 1548 (27.8%) 847 (19.1%) 421 (15.8%) Other/unknown 1635 (16.3%) 804 (14.4%) 831 (18.7%) 507 (19.1%) Region of origin (n (%)) Europe 7498 (74.8%) 4307 (77.3%) 3191 (71.8%) 1918 (72.1%) Sub-Saharan Africa 439 (4.4%) 169 (3.0%) 270 (6.1%) 173 (6.5%) Latin America 1875 (18.7%) 992 (17.8%) 883 (19.9%) 495 (18.6%) Other/unknown 206 (2.1%) 106 (1.9%) 100 (2.3%) 73 (2.7%) CD4 count, cells/µL Median (1st; 3rd quartile) 400 (215 600) 566 (450 739) 189 (75 275) 93 (38 162) < 200 2293 (22.9%) 0 (0.0%) 2293 (51.6%) 2293 (86.2%) 200–350 1943 (19.4%) 0 (0.0%) 1943 (43.7%) 158 (5.9%) 350–500 2061 (20.6%) 2007 (36.0%) 54 (1.2%) 54 (2.0%) ≥ 500 3614 (36.1%) 3567 (64.0%) 47 (1.1%) 47 (1.8%) Unknown 107 (1.1%) 0 (0.0%) 107 (2.4%) 107 (4.0%) Nadir CD4 count, cells/µL Median (1st; 3rd quartile), 351 (192 520) 499 (407 644) 179 (72 263) 89 (36 157) < 200 2235 (22.3%) 29 (0.5%) 2206 (49.6%) 2100 (79.0%) 200–500 4016 (40.1%) 2309 (41.4%) 1707 (38.4%) 179 (6.7%) ≥ 500 2369 (23.6%) 2335 (41.9%) 34 (0.8%) 34 (1.3%) Unknown 1398 (14.0%) 901 (16.2%) 497 (11.2%) 346 (13.0%) CD4/CD8 ratio, Median (1st; 3rd quartile) 0.42 (0.22, 0.66) 0.58 (0.41, 0.81) 0.21 (0.11, 0.36) 0.14 (0.07, 0.23) ≤ 0.4 3841 (38.3%) 1107 (19.9%) 2734 (61.5%) 1798 (67.6%) > 0.4 4225 (42.2%) 3529 (63.3%) 696 (15.7%) 184 (6.9%) Unknown 1952 (19.5%) 938 (16.8%) 1014 (22.8%) 677 (25.5%) Viral load (n (%)), copies/mL < 10,000 1627 (16.2%) 1252 (22.5%) 375 (8.4%) 149 (5.6%) 10,000–100,000 3751 (37.4%) 2315 (41.5%) 1436 (32.3%) 652 (24.5%) > 100,000 3135 (31.3%) 1076 (19.3%) 2059 (46.3%) 1460 (54.9%) Unknown 1505 (15.0%) 931 (16.7%) 574 (12.9%) 398 (15.0%) Aids diagnosis (n (%)) 1339 (13.4%) 0 (0.0%) 1339 (30.1%) 1339 (50.4%) Hepatitis C virus antibodies (n (%)) No 8021 (80.1%) 4615 (82.8%) 3406 (76.6%) 1982 (74.5%) Yes 975 (9.7%) 410 (7.4%) 565 (12.7%) 373 (14.0%) Unknown 1022 (10.2%) 549 (9.8%) 473 (10.6%) 304 (11.4%) Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 Page 5 of 10 Table 1 (continued) All participants, Non-late presenters, Late presenters, Advanced presenters, n = 10,018 n = 5574, 55.6% n = 4444, 44.4% n = 2659, 26.5% Hepatitis B virus surface antigen (n (%)) No 7719 (77.1%) 4117 (73.9%) 3602 (81.1%) 2129 (80.1%) Yes 325 (3.2%) 158 (2.8%) 167 (3.8%) 112 (4.2%) Unknown 1974 (19.7%) 1299 (23.3%) 675 (15.2%) 418 (15.7%) All p-values for the comparisons between late and non-late presenters were < 0.001. All p-values for the comparisons between advanced and non-late presenters were < 0.001 MSM men who have sex with men, IDU injection drug user A B 900 1.0 800 700 Median CD4/CD8 600 Median CD4 500 0.5 400 0.4 300 200 0 6 12 24 36 48 60 72 84 96 108 120 132 0 6 12 24 36 48 60 72 84 96 108 120 132 Months since enrollment Months since enrollment non−LP LP AP Fig. 1 Median CD4/CD8 (A) and CD4 count (B) over time according to late presentation status. non-LP non-late presenters, LP late presenters; AP advanced presenters Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 Page 6 of 10 non−LP LP AP 100 75 % of individuals CD4/CD8 50 = 0.4 >0.4 25 0 0 50 100 150 0 50 100 150 0 50 100 150 Months since enrollment Fig. 2 Percentage of individuals with CD4/CD8 ratio below or above 0.4 over time in non-late, late and advanced presenters. non-LP non-late presenters, LP late presenters; AP advanced presenters in advanced presenters. There was no evidence that the CD8 ratio ≤ 0.4 was also associated with increased association between CD4/CD8 ratio and the clinical out- risk of some specific serious non-AIDS events, such as comes differed between non-late and late presenters (all cardiovascular (1.89; 95%CI 1.19, 3.00) and non-AIDS p-values for interaction > 0.5) or between non-late and defining malignancies (1.52; 95%CI 1.10, 2.12). advanced presenters (all p-values for interaction > 0.1). Overall, compared with CD4/CD8 ratio > 0.4, CD4/ Sensitivity analysis CD8 ratio ≤ 0.4 doubled the risk of experiencing the The analysis including viral load as time-varying variable composite endpoint (HR 2.00; 95%CI 1.63, 2.45), with a was consistent with the main results (data not shown). three-fold increased risk of an AIDS event (3.05; 95%CI In the sensitivity analysis stratified by the timing of ART 2.25, 4.12), and it was also associated with an increased initiation, the association between low CD4/CD8 ratio risk of serious non-AIDS event (1.58; 95%CI 1.27, 1.97), with clinical outcomes was confirmed, regardless on and overall mortality (1.62; 95%CI 1.32, 1.98). CD4/ ART initiation time. In those starting ART within the Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 Page 7 of 10 A Composite endpoint AIDS events 4 4 2 2 Incidence rates x 100 PY 0 0 89 218 246 226 201 151 60 61 104 54 84 39 non−LP LP AP non−LP LP AP Serious non−AIDS events Overall deaths 4 4 CD4/CD8 2 2 ≤ 0.4 >0.4 0 0 39 150 138 162 116 107 25 61 118 94 96 66 non−LP LP AP non−LP LP AP B Cardiovascular events Liver events NADM 1.5 1.5 1.5 Incidence rates x 100 PY 1.0 1.0 1.0 0.5 0.5 0.5 0.0 0.0 0.0 10 51 35 45 31 28 2 14 25 17 22 11 27 90 75 98 62 67 non−LP LP AP non−LP LP AP non−LP LP AP Fig. 3 Incidence rates of the clinical outcomes of interest according to CD4/CD8 ratio over time in in non-late, late and advanced presenters. The figures below each bar correspond to the number of events. non-LP non-late presenters, LP late presenters; AP advanced presenters; NADM non-AIDS defining malignancies 1st year since the enrolment, the HRs for the association Discussion between the CD4/CD8 and the composite endpoint was In this observational study, we found that PLWH with 2.34 (95%CI 1.42, 3.85, n of events = 99) in non-late, 1.86 a CD4/CD8 ratio ≤ 0.4 over time are at a greater risk of (95%CI 1.09, 3.17, n = 507) in late and 1.75 (95%CI 1.28, clinical progression regardless their late presentation 2.40, n = 399) in advanced presenters. In participants status. This corroborates the role of the CD4/CD8 ratio starting ART 1 year after the enrolment or later, the cor- as prognostic marker of clinical outcomes in PLWH no responding HRs were 1.72 (95%CI 1.23, 2.41, n = 239) for matter how they present at diagnosis. Although this non-late, 2.43 (95%CI 1.31, 4.52, n = 54) for late and 1.03 marker has previously shown an association with the (95%CI 0.29, 3.64, n = 27) for advanced presenters. development of AIDS- and non-AIDS-related events in some cohorts of PLWH [8, 9, 16–18] to the best of Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 Page 8 of 10 Table 2 Association between CD4/CD8 ratio over time and clinical outcomes in non-late, late and advanced presenters Non-late p-value Late p-value Interaction Advanced p-value Interaction presenters, presenters, p-value LP presenters, p-value AP CD4/CD8 ≤ 0.4 CD4/CD8 ≤ 0.4 vs non-LP CD4/CD8 ≤ 0.4 vs non-LP vs CD4/ vs CD4/ vs CD4/ CD8 > 0.4 CD8 > 0.4 CD8 > 0.4 Composite Unadjusted HR 2.57 (1.97, 3.35) < 0.001 3.11 (2.33, 4.17) < 0.001 2.55 (1.88, 3.45) < 0.001 endpoint (95%CI) Adjusted HR 1.90 (1.48, 2.43) < 0.001 1.94 (1.46, 2.57) < 0.001 0.869 1.72 (1.26, 2.34) < 0.001 0.598 (95%CI) AIDS events Unadjusted HR 5.80 (3.82, 8.81) < 0.001 4.63 (2.93, 7.33) < 0.001 3.39 (1.99, 5.77) < 0.001 (95%CI) Adjusted HR 3.31 (2.23, 4.93) < 0.001 2.75 (1.78, 4.27) < 0.001 0.365 2.25 (1.34, 3.76) 0.002 0.139 (95%CI) Serious Non- Unadjusted 1.62 (1.16, 2.28) 0.005 2.45 (1.69, 3.55) < 0.001 2.12 (1.41, 3.20) < 0.001 AIDS events HR(95%CI) Adjusted HR 1.39 (0.96, 2.02) 0.079 1.62 (1.10, 2.40) 0.016 0.423 1.49 (0.97, 2.29) 0.069 0.640 (95%CI) Cardiovascular Unadjusted 1.25 (0.57, 2.73) 0.570 2.44 (0.94, 6.35) 0.067 2.50 (0.88, 7.14) 0.087 events HR(95%CI) Adjusted 1.33 (0.64, 2.76) 0.444 1.82 (0.72, 4.61) 0.208 0.511 1.85 (0.67, 5.12) 0.234 0.425 HR(95%CI) Liver events Unadjusted HR 0.84 (0.22, 3.18) 0.792 3.54 (0.81, 15.51) 0.093 3.36 (0.65, 17.44) 0.149 (95%CI) Adjusted HR 0.42 (0.12, 1.50) 0.183 1.54 (0.37, 6.34) 0.565 0.059 1.60 (0.33, 7.71) 0.556 0.078 (95%CI) Neoplasms Unadjusted HR 1.92 (1.34, 2.75) < 0.001 2.27 (1.52, 3.40) < 0.001 1.90 (1.25, 2.88) 0.003 (95%CI) Adjusted HR 1.61 (1.02, 2.56) 0.043 1.56 (0.97, 2.50) 0.066 0.867 0.64 (0.04, 11.32) 0.193 0.500 (95%CI) Overall mortality Unadjusted HR 2.63 (1.57, 4.39) < 0.001 3.85 (2.15, 6.91) < 0.001 3.09 (1.69, 5.64) < 0.001 (95%CI) Adjusted HR 1.49 (0.92, 2.41) 0.103 1.80 (1.04, 3.11) 0.036 0.511 1.61 (0.92, 2.83) 0.095 0.734 (95%CI) CI confidence interval; HR hazard ratio; LP late presenters; AP advanced presenters a HR (CI 95%) were estimated with extended Cox regression models adjusted for age (< 50, ≥ 50 years) and CD4 count (< 500, ≥ 500/µL), both modelled as time-varying covariates, a combined variable of gender and HIV transmission category (MSM, IDU, heterosexual women, heterosexual men, other/unknown), educational level (no studies or primary education, secondary education, university, other/unknown), region of origin (Europe, Sub-Saharan Africa, Latin America, other/unknown), presence of hepatitis C virus antibodies (no, yes or unknown), presence of hepatitis B surface antigen (no, yes or unknown) and viral load (< 10,000, 10,000– 100,000, ≥ 100,000 copies/mL, unknown) at enrolment, and with an interaction term between CD4/CD8 ratio over time and late or advanced presentation our knowledge this is the first study evaluating its role the negative impact of the low CD4/CD8 ratio did not among late and advanced presenters and assessing depend on ART initiation timing or on viral response, whether its clinical impact is the same among the non- suggesting that the prognostic role of the CD4/CD8 ratio late presenters. may be independent on when the treatment is initiated Certainly, late presentation status was found to have and on its effectiveness in terms of viral suppression. a negative impact on both the absolute CD4 cell count The adjusted models suggested an increased risk of and CD4/CD8 ratio recovery, as observed in other stud- serious non-AIDS events associated with low CD4/CD8 ies [18, 19]. Besides, we found that the risk of clinical ratio. This association was observed regardless of late progression, and specifically of AIDS events, was higher presentation status, although it was of lower magnitude when the CD4/CD8 ratio was ≤ 0.4 over time for both than the one observed for the AIDS-related events and non-late and late or advanced presenters. However, in non-late and advanced presenters was quite impre- the negative impact of a CD4/CD8 ≤ 0.4 ratio was also cise. Among non-AIDS events, we observed increased detected among non-late presenters. It is worth high- risk of malignancies, cardiovascular and liver events, lighting that we did not focus on CD4/CD8 ratio val- though with large and imprecise confidence intervals, ues at enrolment or at ART initiation, but on CD4/CD8 probably due to the low number of events in each cat- ratio values measured over time. We also observed that egory. Our results are in discordance with those of two Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 Page 9 of 10 previous studies. Castilho et al. [20] observed no asso- Conclusions ciation between baseline CD4/CD8 ratio and risk of In conclusion, a low CD4/CD8 ratio measured over time non-AIDS events in a cohort of virologically suppressed is associated with an increased risk of morbidity and HIV-positive adults, independently of the CD4+ cell mortality in PLWH independently of their late presenta- count. These results are not directly comparable with tion status. These preliminary findings support the prog- ours, as the authors did not include time-varying CD4/ nostic role of variation of CD4/CD8 ratio over time in CD8 ratio as predictor and they estimated HRs for 0.1 this highly vulnerable subpopulation and can help define increase in the CD4/CD8 ratio. Using similar methods the subgroup of service users who may need closer moni- to those in our study, Hema et al. [21] did find inconclu- toring to avoid comorbidities, thus optimizing the follow- sive estimates of the association between time-varying up and the use of healthcare resources. CD4/CD8 ratio ≥ 0.5 (vs CD4/CD8 < 0.5) and serious non-AIDS events considered overall, when control- Abbreviations ling for time-varying CD4 count. The discrepancy with ART​: Active antiretroviral treatment; CD4/CD8ratio: CD4+ T cells/CD8+ T cells our results may depend on the different definition of ratio; CI: Confidence intervals; CoRIS: Cohort of the Spanish HIV/AIDS Research non-AIDS events, while, in line with our findings, the Network; HR: Hazard ratio; PLWH: People living with HIV. authors observed that low CD4/CD8 ratio was associ- ated with increased risk of non-AIDS defining cancers. Supplementary Information The higher risk of non-AIDS events found in our The online version contains supplementary material available at https://​doi.​ org/​10.​1186/​s12879-​022-​07352-z. study could be explained by increased inflammation and immunoactivation, that have been already identi- fied as potential mechanisms for both atherosclerosis Additional file 1. Title of data: Cohort of the Spanish HIV/AIDS Research Network (CoRIS). Description of data: Centres and investigators involved [22] and malignancies [23] in PLWH. Thus, our find- in CoRIS. ings bring to light the presence of those phenomena specifically in individuals with low CD4/CD8 ratio [8]. Acknowledgements Some authors have in fact reported a lower CD4/CD8 This study would not have been possible without the collaboration of all ratio in PLWH diagnosed with a cardiovascular event patients, medical and nursery staff and data mangers who have taken part in when compared to those without [9, 20]. Besides, ear- the Project. lier studies describe an association between the inver- Author contributions sion of the CD4/CD8 ratio and surrogate markers of All authors were involved in the setting up of the cohort and contributed to vascular disease, such as the carotid intima-media its design. All authors were involved in data collection. LDD and MR drafted the paper, under the supervision of IJ. MR planned and realized the statistical thickness [24, 25] and arterial stiffness [24]. In terms analyses, OB contributed to the study design and the manuscript writing, RR, of neoplasms, Serrano et al. [9] found lower CD4/CD8 JAI, SM and IJ planned the study. LLC, JP, DP, JO, DF reviewed the manuscript. ratio in participants diagnosed with non-AIDS defin- All authors read and approved the final manuscript. ing malignancies in comparison with those without a Funding cancer diagnosis. A longer follow-up of our cohort it is The RIS cohort (CoRIS) is supported by the Instituto de Salud Carlos III desirable as it will allow us to observe more events and through the Red Temática de Investigación Cooperativa en Sida (RD06/006, RD12/0017/0018 and RD16/0002/0006) as part of the Plan Nacional R+D+I therefore make more reliable estimates to confirm the and cofinanced by ISCIII-Subdirección General de Evaluación y el Fondo impact of low CD4/CD8 ratio on clinical outcomes. Europeo de Desarrollo Regional (FEDER)”. This study has received funding from We acknowledge that our analysis is not adjusted for Gilead Sciences. The funding body did not participate in the design of the study and collection, analysis, and interpretation of data and in writing the some potential confounder factors, such as smoking manuscript. status. Nevertheless, other studies showed higher risk of lung cancer associated with low CD4/CD8 ratio even Availability of data and materials The datasets used and/or analysed during the current study are available from after accounting for smoking status [26, 27]. As further the corresponding author on reasonable request. limitation, we did not consider the effect of ART regi- mens, which may vary according to initial CD4 count. Declarations We also could not classify as late or non-late presenters those who did not have CD4 count or AIDS events avail- Ethics approval and consent to participate The CoRIS cohort was approved by the Research Ethic Committee of the able before starting treatment, although they accounted Gregorio Marañón Hospital and the study was approved by the Research Ethic for only 3% of the entire cohort. Finally, although cohort Committee of the “12 de Octubre” Hospital (Number 14/080). All the patients participants were followed for an extended period, their signed informed consent to participate in the CoRIS cohort. young age may decrease our ability to evaluate outcomes Consent for publication which develop only over the long-term and later in life. Not applicable. Domínguez‑Domínguez et al. BMC Infectious Diseases (2022) 22:379 Page 10 of 10 Competing interests activation, and increased risk of non-AIDS morbidity and mortality. PLoS MR has received a grant from Gilead Science. IJ has received teaching fees Pathog. 2014;10(5):e1004078. from Viiv and advisory fees from Gilead Science. SM has been involved in 9. Serrano-Villar S, Pérez-Elías MJ, Dronda F, Casado JL, Moreno A, Royuela speaking activities and has received grants for research from Gilead, Janssen A, et al. Increased risk of serious non-AIDS-related events in HIV-infected Cilag, Merck Sharp&Dohme, and ViiV Healthcare. RR reports personal fees from subjects on antiretroviral therapy associated with a low CD4/CD8 ratio. ViiV Healthcare and Merck Sharp & Dohme; grants and personal fees from PLoS ONE. 2014;9(1):e85798. Gilead Sciences and Janssen Cilag. OB reports payments for lectures by Gilead 10. The Strategies for Management of Antiretorviral Therapy (SMART) Study Sciences and ViiV Healthcare, and non-financial support for national confer‑ Group. Major clinical outcomes in antiretroviral therapy (ART)–naive par‑ ence and national HIV courses from ViiV Healthcare and Merck Sharp and ticipants and in those not receiving ART at baseline in the SMART study. J Dohme, outside the submitted work. LD has received honoraria for lectures Infect Dis. 2008;197:1133–44. by Gilead Sciences and ViiV Healthcare, and non-financial support for HIV 11. Caro-Murillo AM, Castilla J, Pérez-Hoyos S, Miró JM, Podzamczer D, conferences and courses from Gilead, ViiV Healthcare and Merck Sharp and Rubio R, et al. 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