Hepatitis C: global epidemiology and strategies for control

It is estimated that globally there are approximately 100 million persons with serological evidence of current or past HCV infection, and that HCV causes about 700 000 deaths each year. The prevalence of infection is the highest in lower and middle income countries, in which a significant number of past infections were caused by iatrogenic transmission and sub-optimal injection safety. In contrast, in developed countries, infections are caused mainly by high-risk exposures and behaviours among specific populations, such as persons who inject drugs. Recently, new direct antiviral activity (DAA) oral drugs with high rates of cure over short duration, which are well tolerated, have made chronic hepatitis C a curable condition. The extraordinary clinical performance of DAAs and recent substantial price reductions and expansion in access in resource-limited settings has provided new impetus for potential control and elimination of hepatitis C as a public health threat. We review the global epidemiology of HCV and the opportunities for preventative and treatment interventions to achieve global control of HCV infection. We also summarize the key elements of the World Health Organization's first-ever global health sector strategy for addressing the viral hepatitis pandemic.

Wide variation in estimates of global prevalence and burden of chronic hepatitis B and C infection cited in published literature

To evaluate the extent of heterogeneity in global estimates of chronic hepatitis B (HBV) and C (HCV) cited in the published literature, we undertook a systematic review of the published literature. We identified articles from 2010 to 2014 that had cited global estimates for at least one of ten indicators [prevalence and numbers infected with HBV, HCV, HIV-HBV or HIV-HCV co-infection, and mortality (number of deaths annually) for HBV and HCV]. Overall, 488 articles were retrieved: 239 articles cited a HBV-related global estimate [prevalence (n = 12), number infected (n = 193) and number of annual deaths (n = 82)]; 280 articles had HCV-related global estimates [prevalence (n = 86), number infected (n = 203) and number of annual deaths (n = 31)]; 31 had estimates on both HBV and HCV; 54 had HIV-HBV co-infection estimates [prevalence (n = 42) and number co-infected (n = 12)]; and 68 had estimates for HIV-HCV co-infection [prevalence (n = 40) and number co-infected (n = 28)]. There was considerable heterogeneity in the estimates cited and also a lack of consistency in the terminology used. Although 40% of 488 articles cited WHO as the source of the estimate, many of these were from outdated or secondary sources. Our findings highlight the importance of clear and consistent communication from WHO and other global health agencies on current consensus estimates of hepatitis B and C burden and prevalence, the need for standardisation in their citation, and for regular updates.

Sexual risk behaviours and sexual health outcomes among heterosexual black Caribbeans: comparing sexually transmitted infection clinic attendees and national probability survey respondents

We compared sociodemographic characteristics, sexual risk behaviours and sexual health experiences of 266 heterosexual black Caribbeans recruited at a London sexual health clinic between September 2005 and January 2006 with 402 heterosexual black Caribbeans interviewed for a British probability survey between May 1999 and August 2001. Male clinic attendees were more likely than men in the national survey to report: ≥10 sexual partners (lifetime; adjusted odds ratio [AOR]: 3.27, 95% confidence interval [CI]: 1.66-6.42), ≥2 partners (last year; AOR: 5.40, 95% CI: 2.64-11.0), concurrent partnerships (AOR: 3.26, 95% CI: 1.61-6.60), sex with partner(s) from the Caribbean (last 5 years; AOR: 7.97, 95% CI: 2.42-26.2) and previous sexually transmitted infection (STI) diagnosis/diagnoses (last 5 years; AOR: 16.2, 95% CI: 8.04-32.6). Similar patterns were observed for women clinic attendees, who also had increased odds of termination of pregnancy (AOR: 3.25, 95% CI: 1.87-5.66). These results highlight the substantially higher levels of several high-risk sexual behaviours among UK black Caribbeans attending a sexual health clinic compared with those in the general population. High-risk individuals are under-represented in probability samples, and it is therefore important that convenience samples of high-risk individuals are performed in conjunction with nationally representative surveys to fully understand the risk behaviours and sexual health-care needs of ethnic minority communities.

Patterns and predictors of the use of different antiretroviral drug regimens at treatment initiation in the UK

BACKGROUND

We describe the patterns of antiretroviral drug use at treatment initiation from 1996 to 2005 in a large UK multicentre cohort.

METHODS

We examined trends over time and across 10 clinical sites in stage of disease and type of antiretroviral therapy (ART). Multivariable regression was used to identify factors associated with the CD4 cell count at ART initiation, and with the choice of a protease inhibitor (PI) over a nonnucleoside reverse transcriptase inhibitor (NNRTI), and use of nevirapine over efavirenz.

RESULTS

A total of 14 252 patients initiated ART, of whom 54% had a CD4 count <200 cells/microL. The most important predictors of starting ART at a lower CD4 cell count were being male, nonwhite, and heterosexual or an injecting drug user (P<0.0001). Among those starting ART, the use of highly active ART increased from 23% in 1996 to >96% from 2000 onwards. There were differences over time and across the clinics in the use of PIs vs. NNRTIs, in the choice of specific PIs, NNRTIs and nucleoside reverse transcriptase inhibitor (NRTI) backbone, and in the rate at which prescribing practices changed.

CONCLUSIONS

Clinic site and calendar year were important determinants of choice of drug at ART initiation, whereas clinical and demographic characteristics were more important in influencing the CD4 cell count at initiation of ART.

Incidence and Risk Factors for Immune Reconstitution Inflammatory Syndrome in an Ethnically Diverse HIV Type 1-Infected Cohort

BACKGROUND

It is estimated that 10%-25% of patients who start highly active antiretroviral therapy (HAART) experience immune reconstitution inflammatory syndrome (IRIS). Our objective was to determine the incidence, clinical spectrum, and predictors of IRIS in an ethnically diverse cohort of patients initiating HAART.

METHODS

A retrospective study of all patients starting HAART between 1 January 2000 and 31 August 2002 at a human immunodeficiency virus (HIV) clinic in London was performed. All laboratory measurements and data on antiretroviral therapies were obtained from the clinic database. Medical records were reviewed to identify clinical events consistent with IRIS during the 6 months after HAART was initiated.

RESULTS

A total of 199 patients were included, of whom 50.8% were male, 59.3% were black African, 29.1% were white, and 10.5% were black Caribbean. The median baseline CD4 cell count and HIV RNA load were 174x10(6) cells/L (interquartile range [IQR], 82-285x10(6) cells/L) and 37,830 copies/mL (IQR, 4809-149,653 copies/mL), respectively. Forty-four patients (22.7%) experienced an IRIS event at a median of 12 weeks after HAART initiation (IQR, 4-24 weeks after initiation); 22 events (50%) involved genital herpes, 10 (23%) involved genital warts, 4 (9.0%) involved molluscum contagiosum, and 4 (9.0%) involved varicella zoster virus infection. Five patients had mycobacterial infections, 4 had hepatitis B, 1 had Pneumocystis jirovecci infection, and 1 had Kaposi sarcoma. The strongest independent predictors of IRIS were younger age at initiation of HAART (P=.003), baseline CD4 cell percentage of <10% (odds ratio [OR], 2.97; IQR, 1.17-7.55) compared with >15%, and ratio of CD4 cell percentage to CD8 cell percentage of <0.15 (OR, 3.45; 95% confidence interval, 1.27-9.1) compared with >0.3.

CONCLUSIONS

Approximately one-quarter of patients who start HAART experience an IRIS event. The majority are dermatological, in particular genital herpes and warts. Patients with advanced immunodeficiency at HAART initiation are at greatest risk of developing IRIS and should be appropriately screened and monitored.

Prevalence of hepatitis C in an ethnically diverse HIV-1-infected cohort in south London

OBJECTIVES

There is limited information on the prevalence of and risk factors for hepatitis C virus (HCV) infection among HIV-1-infected patients in the UK. Our objective was to determine the prevalence of HCV infection among an ethnically diverse cohort of HIV-infected patients in south London, and to extrapolate from these data the number of co-infected patients in the UK.

METHODS

A total of 1017 HIV-1-infected patients who had attended King's College Hospital HIV clinic between September 2000 and August 2002 were screened for HCV antibody using a commercial enzyme-linked immunosorbent assay (ELISA). Positive results were confirmed by polymerase chain reaction (PCR) or recombinant immunoblot assay. Demographic, clinical and laboratory data were obtained from the local computerized database and medical records. We applied our HCV prevalence rates in the different HIV transmission groups to the estimated number of HIV-infected persons in these groups in the UK, to obtain a national estimate of the level of HIV-HCV co-infection.

RESULTS

Of the 1017 HIV-1-infected patients, 407 (40%) were white men, 158 (15.5%) were black African men, 268 (26.3%) were black African women, and 61 (6%) and 26 (2.6%) were black Caribbean men and women, respectively. Heterosexual exposure was the most common route of HIV acquisition (53.5%), followed by men having sex with men (36.9%), and current or previous injecting drug use (IDU) (7.2%). The overall prevalence of HCV co-infection was 90/1017 (8.9%), but this varied substantially according to route of transmission, from 82.2% among those with a history of IDU (which accounted for 67% of all HCV infections), to 31.8% in those who had received blood products, to 3.5% and 1.8% in those with homosexually and heterosexually acquired infection, respectively. Multivariate logistic regression analysis identified several independent risk factors for HCV infection: a history of IDU [odds ratio (OR) = 107.2; 95% confidence interval (CI) = 38.5-298.4], having received blood products (OR = 16.5; 95% CI = 5.1-53.7), and either being from a white ethnic group (OR = 4.3; 95% CI = 1.5-12.0) or being born in Southern Europe (OR = 6.7; 95% CI = 1.5-30.7). Based on the 35,473 known HIV-1-infected persons in the UK and the 10 997 estimated to be unaware of their status, we projected that there are at least 4136 HIV-HCV co-infected individuals in the UK and 979 who are unaware of their status.

CONCLUSIONS

Overall, 9% of our cohort was HIV-HCV co-infected. The prevalence was highest among intravenous drug users (82%), who accounted for most of our HCV cases, and lowest among heterosexual men and women from sub-Saharan Africa and the Caribbean [< 2%]. Our estimate that a significant number of co-infected persons may be unaware of their HIV and HCV status, highlights an urgent need to increase the uptake of HCV and HIV testing, particularly among injecting drug users, to reduce the risk of onward transmission.

Antiretroviral therapies in HIV-1 infection

Recent progress in our understanding of the viral dynamics and immunobiology of HIV infection, coupled with the introduction of a new generation of antiretroviral agents, has led to significant advances in the medical management of HIV infection. Eleven antiretroviral drugs are currently licensed in the United States, and eight are licensed in Europe. These include the nucleoside reverse transcriptase inhibitors (AZT, ddI, ddC, 3TC and d4T); the non-nucleoside reverse transcriptase inhibitors (nevirapine and delavirdine) and the protease inhibitors (saquinavir, indinavir and ritonavir). This report summarises recent developments in the use of antiretroviral therapies and the main treatment strategies under evaluation in current trials. These strategies include the evaluation of novel antiretroviral agents; combinations to achieve maximal viral suppression; optimal sequencing of antiretroviral agents; and subtraction therapy. However, many important issues in the use of antiretroviral therapies remain unresolved, including the optimal role of new agents, such as protease inhibitors (PIs), and the use of triple combination therapy in initial and subsequent treatment regimens; when therapy should be changed; which alternative agents should then be used; and the most appropriate methods for monitoring the efficacy of therapy.

Ethnic differences in stage of presentation of adults newly diagnosed with HIV-1 infection in south London

OBJECTIVES

To establish whether there were ethnic differences in demographic characteristics, the stage at HIV diagnosis and reasons for and location of HIV testing between 1998 and 2000 in a large ethnically diverse HIV-1-infected clinic population in south London in the era of highly active antiretroviral therapy.

METHODS

A retrospective review was carried out of all persons >18 years old attending King's College Hospital with a first positive HIV-1 test between 1 January 1998 and 31 October 2000, and of a random sample of patients attending St Thomas' hospital with a first positive HIV-1 test in the same period. Demographic data, details of reasons for and site of HIV test, clinical stage, CD4 lymphocyte count and HIV-1 viral load at HIV diagnosis were abstracted from the local database and medical records. Comparisons were made according to ethnic group (white, black African and black Caribbean) and over time (1998, 1999 and 2000).

RESULTS

Of the 494 patients with new HIV-1 diagnoses between January 1998 and December 2000, 179 (36.2%) were white, 270 (54.7%) were black African and 45 (9.1%) were black Caribbean. There were significant differences across the ethnic groups in HIV risk group, reasons for and site of HIV testing, and clinical and CD4 stage at diagnosis. Among whites, 72.6% were men who had sex with men, 3.4% injecting drug users and 21.2% heterosexuals, compared to 2.2%, 0.4% and 93.3% among black Africans, and 28.9%, 0% and 68.9% among black Caribbeans (P<0.001). Black Africans were more likely to present with an AIDS diagnosis (21.3%) and a lower CD4 cell count [223 cells/microL; interquartile range (IQR) 88-348] compared to both whites (9.9%; 358 cells/microL; IQR 151-508) and black Caribbeans (17.9%; 294 cells/microL; IQR 113-380), who were intermediate between whites and black Africans in their stage of presentation. There was a statistically nonsignificant trend with time, between 1998 and 2000, towards earlier diagnosis based on the CD4 cell count in whites (323 and 403 cells/microL) and black Caribbeans (232 and 333 cells/microL), but a later diagnosis in black Africans (233 and 175 cells/microL). The majority of black Africans were HIV-tested as a result of suggestive symptoms or antenatal screening (58.4%) rather than because of perceived risk (40.5%), in contrast to the situation in whites (24.1% vs. 71.7%, respectively) or black Caribbeans (34.5% vs. 65.5%, respectively) (P<0.001). We found no significant differences across ethnic groups in age, HIV-1 viral load or year of HIV diagnosis.

CONCLUSIONS

Black Africans continue to present with more advanced HIV disease than whites or black Caribbeans, with no evidence of any trend towards earlier diagnosis. Future educational campaigns designed to promote the uptake of HIV testing among black Africans and black Caribbeans will need to address the multiple barriers to testing, including misperception of risk, stigma and ready access to testing.

CD4 responses to conserved HIV-1 T helper epitopes show both negative and positive associations with virus load in chronically infected subjects

Characterization of immune responses to immunodominant CD4 epitopes in HIV-1 that are associated with control of HIV infection could be used to strengthen the efficacy of polyepitope HIV vaccines. We measured both the proliferative and the CD4 interferon (IFN)-gamma and interleukin (IL)-2 cytokine responses specific for 11 previously identified HIV-1 T helper epitopes in 10 HIV-infected non-progressors (LTNPs) (infected for a median of 15 years with a stable CD4 count of >500 cells x 10(6)/l), and seven slow progressors (SPs) (infected for a median of 15 years with a CD4 count that had declined to <500 cells x 10(6)/l). Both groups were antiretroviral treatment-naive at the time of evaluation. The median virus load of SP group was higher than that of the LTNP group (P = 0.0002). The CD4 response to a peptide pool representing all potential CD4 Gag epitopes and to Gag p24 protein was also studied. Compared to SPs, LTNPs had higher numbers of Gag-specific IFN-gamma+IL-2+ CD4s (P = 0.0059). The Gag-specific cytokine and proliferative responses correlated inversely with virus load (P = 0.03 and 0.0002, respectively), highlighting the potential importance of this response in immunity to HIV. A direct correlation was noted between proliferation and the Gag-specific IL-2 (P = 0.0053) rather than IFN-gamma response (P = 0.1336), demonstrating that the proliferation assay reflected the IL-2 rather than the IFN-gamma secreting capacity of CD4 cells. Several subjects with diverse class II DRB1 alleles responded, confirming the 11 selected peptides to be both antigenic and conserved. CD4 cytokine responses to one Gag and two conserved Pol peptides correlated negatively with virus load. The cytokine response to two additional Pol peptides correlated positively with virus load. The data indicate that there is not an absolute correlation between the CD4 immune response to conserved and broadly antigenic helper T cell epitopes in HIV non-progression.

Epidemiological risk factors for hypersensitivity reactions to abacavir

We investigated risk factors for hypersensitivity reactions (HSR) to abacavir in a case-control study. In a multivariate analysis, white race [odds ratio (OR), 5.16; 95% confidence interval (CI), 1.16-22.97] and a higher CD8 cell count at initiation of abacavir (>850 vs. < or =850 cells: OR, 3.74; 95% CI, 1.19-11.77) were found to be significantly associated with the development of HSR. Age, gender, stage of disease, prior antiretroviral exposure and type of concurrent antiretroviral therapy were not associated with HSR. Differences in predisposition to HSR according to ethnicity and baseline CD8 cell count may be explained by the reported MHC genetic associations with HSR.

Impact of human immunodeficiency virus (HIV) infection on the progression of liver fibrosis in hepatitis C virus infected patients

OBJECTIVES

To compare the rate of hepatic fibrosis progression in hepatitis C virus (HCV) infected and human immunodeficiency virus (HIV)-HCV coinfected patients, and to identify factors that may influence fibrosis progression.

PATIENTS AND METHODS

A total of 153 HCV infected and 55 HCV-HIV coinfected patients were identified from two London hospitals. Eligible patients had known dates of HCV acquisition, were HCV-RNA positive, and had undergone a liver biopsy, which was graded using the Ishak score. Univariate and multivariate logistic regression analyses were used to identify factors associated with fibrosis progression rate and the development of advanced fibrosis (stages 3 and 4).

RESULTS

The estimated median fibrosis progression rate was 0.17 units/year (interquartile range (IQR) 0.10-0.25) in HIV-HCV coinfected and 0.13 (IQR 0.07-0.17) in HCV monoinfected patients (p=0.01), equating to an estimated time from HCV infection to cirrhosis of 23 and 32 years, respectively. Older age at infection (p<0.001), HIV positivity (p=0.019), higher alanine aminotransferase (ALT) level (p=0.039), and higher inflammatory activity (p<0.001) on first biopsy were all independently associated with more rapid fibrosis progression. ALT was correlated with histological index (r=0.35, p<0.001). A CD4 cell count < or =250 x 10(6)/l was independently associated with advanced liver fibrosis (odds ratio 5.36 (95% confidence interval 1.26-22.79)) and was also correlated with a higher histological index (r=-0.42, p=0.002).

CONCLUSION

HIV infection modifies the natural history of HCV by accelerating the rate of fibrosis progression by 1.4 fold, and the development of advanced fibrosis threefold. A low CD4 cell count was independently associated with advanced disease and correlated with higher histological index, which suggests that early antiretroviral therapy may be of benefit in slowing HCV progression in coinfected patients.

Comparison between HIV- and CMV-specific T cell responses in long-term HIV infected donors

The mechanisms underlying non-progression in HIV-1 infection are not well understood; however, this state has been associated previously with strong HIV-1-specific CD8+ T cell responses and the preservation of proliferative CD4+ T cell responses to HIV-1 antigens. Using a combination of interferon-gamma (IFN-gamma) ELISpot assays and tetramer staining, the HIV-1-specific CD8+ T cell populations were quantified and characterized in untreated long-term HIV-1-infected non-progressors and individuals with slowly progressive disease, both in relation to CD4+ T cell responses, and in comparison with responses to cytomegalovirus (CMV) antigens. High levels of CD8+ T cell responses specific for HIV-1 or CMV were observed, but neither their frequency nor their phenotype seemed to differ between the two patient groups. Moreover, while CMV-specific CD4+ T cell responses were preserved in these donors, IFN-gamma release by HIV-1-specific CD4+ T cells was generally low. These data raise questions with regard to the role played by CD8+ T cells in the establishment and maintenance of long-term non-progression.

Low prevalence of antiretroviral drug resistance among HIV-1 seroconverters in London, 1984-1991

OBJECTIVES

To examine the prevalence of resistance mutations and natural polymorphisms to reverse transcriptase (RT) and protease inhibitors in a cohort of patients with defined seroconversion dates.

METHODS

Eligible patients were those attending an HIV centre in North London who seroconverted from HIV negative to positive status between 01/01/85 and 31/12/91 (n=104). Genotypic resistance analysis was performed on the first positive serum sample after seroconversion and before use of antiretroviral therapy using population-based sequencing of RT-PCR fragments and rule-based sequence interpretation (Vircogen).

RESULTS

Protease and RT sequences were successfully amplified from only 37 (35.6%) of the 104 seroconverters. Only one patient who seroconverted in August 1991 showed any evidence of significant mutations in the RT region, and this was associated with resistance to zidovudine (ZDV) (215Y and 210W). An additional patient who seroconverted in July 1991 had a TOR mutation and was classified as having intermediate resistance to ZDV. No spontaneous mutations were detected in the protease region.

CONCLUSIONS

Overall only 2 (5%) of these treatment-naïve individuals were infected with HIV variants resistant to ZDV. Although the data at present do not support the need for pretreatment genotyping, there is a need for continued surveillance of the frequency of resistance mutations in antiretroviral naïve patients since the introduction of highly active antiretroviral therapy.

Variable fate of virus-specific CD4(+) T cells during primary HIV-1 infection

Impairment of CD4(+) T lymphocyte responses to human immunodeficiency virus (HIV)-derived antigens is the classic immunological defect observed during the chronic phase of HIV-1 infection. Early intervention with potent antiretroviral therapy (ART) can preserve HIV-specific CD4(+) T lymphocyte reactivity, providing indirect evidence that such responses are mounted during primary infection and subsequently lost in the majority of infected individuals. Here, we demonstrate early and dramatic expansions of functional HIV-specific CD4(+) T lymphocyte frequencies directly ex vivo. These responses are initially of broad specificity, and can disappear rapidly during the natural course of primary infection. This process of loss is variable, such that the rapidity and extent of functional compromise differs between individuals. Institution of ART during these early phases of HIV-1 infection preserves patterns of functional reactivity within the HIV-specific CD4(+) T lymphocyte population. However, there was no evidence for the restoration of deleted responses. These findings indicate that, in some individuals at least, ART must be administered within a narrow window of opportunity during primary HIV-1 infection to effect substantial immune preservation.

Does an HIV clinical trial information booklet improve patient knowledge and understanding of HIV clinical trials?

OBJECTIVES

To evaluate the impact of an information booklet on HIV clinical trials, Clinical Trials in HIV and AIDS: Information For People Who Are Thinking About Joining a Trial, in addition to the standard trial information (SI) on patients' knowledge; understanding and attitudes about clinical trials; and to investigate patients' motivations and reasons for enrolling or not enrolling in a clinical trial.

METHODS

Fifty HIV-1 positive patients who attended the HIV clinic at a west London hospital were randomized to receive either SI alone (n = 27) or SI and a 16 page information booklet explaining the principles and procedures of HIV clinical trials (n = 23). A self-administered questionnaire was used at baseline to assess past experience and attitudes to clinical trials (10 questions), knowledge and understanding of HIV treatments (8 questions) and clinical trials (11 questions). At 2-6 months after randomization, a second interviewer-administered questionnaire addressed the patient's assessment of the usefulness and comprehensiveness of the information provided by the SI and information booklet, whether or not the patient had enrolled in a clinical trial and reasons for enrolling/not enrolling, knowledge of specific aspects of the trial protocol the patient was eligible to join (13 questions) and general knowledge of clinical trial procedures (repeat of 11 baseline questions). Changes in the attitudes and scores on knowledge and understanding of clinical trials were compared for the two groups.

RESULTS

In both groups, patient knowledge of clinical trial procedures improved significantly over the study period. The median score increased from 30 at baseline to 35/44 at follow-up (SI only) vs. 24-31/44 (SI plus booklet), but this did not differ significantly between the two groups. However, knowledge of the specific trial protocol was poor [median score 13/25, interquartile range (IQR) 8-14], and there was no difference in the scores for the two groups. The prime motivations for joining a clinical trial were to benefit personal health and to gain access to new treatments. Potential side-effects were the main concern of prospective trial participants.

CONCLUSIONS

This small trial shows that, while the patients' general knowledge and understanding of clinical trials improved over time, this was not improved by the information booklet and recollection of the details of the relevant trial protocol remained poor.

The metabolic toxicities of antiretroviral therapy

Since the adoption of highly active antiretroviral therapy (HAART) in the mid-1990s, certain metabolic toxicities have been increasingly recognized. These include a fat redistribution syndrome (lipohypertrophy, lipoatrophy), hyperlipidaemia, altered glucose metabolism and insulin resistance, mitochondrial toxicity (presenting as anaemia, myopathy, pancreatitis, neuropathy, hepatic steatosis and lactic acidosis), and bone density abnormalities (osteoporosis and osteonecrosis). Metabolic complications are principally reported with protease inhibitors and nucleoside reverse transcriptase inhibitors, but may be seen with all classes of antiretroviral therapy. In this review, we summarize the epidemiology, pathogenesis and management of these various toxicities.

Incidence and risk factors for the development of indinavir-associated renal complications

OBJECTIVES

To describe the incidence and risk factors for the development of indinavir-associated renal complications (IRC), and subsequent clinical outcome.

PATIENTS AND METHODS

This was a retrospective cohort study based on two large HIV centres in London. Eligible patients received indinavir for at least 1 week between 1 December 1995 and 28 February 1999. Development of IRC was ascertained by case-note review. Multivariate logistic regression and Cox Proportional Hazard's model analysis were used to determine independent risk factors for the development of IRC.

RESULTS

781 patients were eligible. Median CD4 count and viral load at indinavir initiation were 117 x 10(6) cells/L and 47 332 copies/mL, respectively. Median indinavir exposure was 53 weeks (IQR: 20-83). Many patients received other potentially nephrotoxic drugs during indinavir treatment: co-trimoxazole (46%), aciclovir (33%) or both (20%). Overall IRC incidence was 7.3% (6.7 per 100 person-years indinavir exposure). Cases presented with loin pain (58%), renal colic (42%) or dysuria (19%). Identified precipitating events (26%) included fluid depletion or altered indinavir regimen. In the majority of cases indinavir therapy was continued and there was no progressive rise in creatinine levels. In the multivariate analysis, for indinavir treatment >74 weeks there was a reduced risk of developing IRC (OR = 0.23, 95% CI 0.09-0.57, P = 0.001). Concomitant aciclovir increased the IRC risk (OR = 1.99, 95% CI 1.14-3.51, P = 0.016). Factors not associated with outcome were age, gender, ethnicity, baseline CD4 count and viral load, concomitant co-trimoxazole, or use of specific antiretrovirals.

CONCLUSION

An overall IRC incidence of 7.3% was identified. Concomitant aciclovir doubled the risk of IRC and we therefore recommend careful monitoring when prescribing aciclovir with indinavir. A precipitating event was identified in 26% of IRC cases, many of which could have been avoided.

An association of disseminated Mycoplasma fermentans in HIV-1 positive patients with non-Hodgkin's lymphoma

We examined the relationship between the haematogenous dissemination of Mycoplasma fermentans and non-Hodgkin's lymphoma (NHL) in 265 HIV-1 positive patients. A polymerase chain reaction (PCR) assay was used to detect M. fermentans in peripheral blood mononuclear cells (PBMCs) from 50 patients enrolled consecutively from an HIV outpatient clinic in 1991 (cohort 1), 56 patients with lower respiratory tract infection who underwent bronchoscopy in 1992 (cohort 2), and 159 patients who were enrolled into a natural history cohort study in 1994 (cohort 3). The incidence of NHL among the patients was determined in 1998. The PBMCs of 29 patients (10.9%) were positive for M. fermentans (8 in cohort 1, 13 in cohort 2 and 8 in cohort 3) and 11 patients (4.2%) developed NHL which was confirmed histologically (3 in cohort 1, 4 in cohort 2 and 4 in cohort 3). We found a statistically significant association between the presence of M. fermentans and the development of NHL in the combined cohort (risk ratio [RR]=6.78 [95% confidence interval (CI) 2.21--20.84], P=0.003 Fisher's exact test [FET]). This association remained significant even after adjustment in a multivariate analysis for CD4 cell count and HIV disease status at the time of M. fermentans testing (RR=7.97 [95% CI=2.16--29.47], P=0.002).

Comparison of virologic, immunologic, and clinical response to five different initial protease inhibitor-containing and nevirapine-containing regimens

CONTEXT

The effectiveness of different protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitors outside the setting of clinical trials has not been well described.

OBJECTIVES

To compare five different PI-and nevirapine (NVP)-containing regimens on virologic, immunologic, and clinical outcomes and treatment discontinuation.

DESIGN AND SETTING

Observational cohort study based on an HIV clinic in London.

PATIENTS

A total of 690 patients who received either saquinavir hard gel (SQV HG) (n = 183), indinavir (IDV) (n = 189), nelfinavir (NFV) (n = 109), ritonavir (RTV) (n = 42), ritonavir with saquinavir hard gel (RTV/SQV HG) (n = 45), or NVP (n = 122) as part of an initial PI-or NVP-containing treatment regimen between November 1994 and December 1998. A total of 351 (51%) patients had prior exposure to nucleoside reverse transcriptase inhibitors (NRTIs).

MAIN OUTCOME MEASURES

The main outcome measures were virologic undetectability, subsequent virologic rebound, CD4 cell count rise, development of AIDS, and treatment discontinuation. All analyses were stratified for year of initiation of the PI-or NVP-containing regimen.

RESULTS

Overall, 63% of patients attained an undetectable viral load (VL) within 6 months of starting their PI or NVP regimen. The adjusted relative hazard (95% confidence interval [CI]) for an undetectable VL relative to SQV HG was (in rank order): 2.77 (CI: 1.84-4.17) for NFV, 2.54 (CI: 1.81-3.57) for IDV, 2.43 (CI: 1.52-3.87) for RTV, 2.08 (CI: 1.28-3.37) for RTV/SQV HG, and 1.96 (CI: 1.35-2.85) for NVP. Forty-nine percent of patients experienced VL rebound within 12 months of initial attainment of undetectability, but relative to SQV HG, this did not differ significantly across the different PI and NVP regimens. The CD4 cell count response and rate of AIDS events were also similar across the different regimens. No independent predictors of VL undetectability were identified, but prior NRTI exposure was associated with VL rebound, and a lower baseline VL and CD4 cell count were associated with a reduced CD4 count response. The frequency (95% CI) of treatment discontinuation differed across the regimens; at 6 months, it was lowest for NFV (18% [CI: 13%-24%]), IDV (25% [CI: 22%-29%]), and NVP (28% [CI: 22%-34%]) and highest for RTV (41% [CI: 31%-52%]) and SQV HG (52% [CI: 48%-57%]).

CONCLUSIONS

Although PI- and NVP-containing regimens were similar in their CD4 cell count response and rates of subsequent VL rebound, differences were observed in time to VL undetectability and discontinuation rates relative to SQV HG. SQV HG was consistently inferior to the other PIs and NVP. The use of NFV and IDV was associated with the highest rates of undetectability, and together with NVP, the lowest rates of discontinuation.

Direct ex vivo analysis reveals distinct phenotypic patterns of HIV-specific CD8(+) T lymphocyte activation in response to therapeutic manipulation of virus load

Therapeutic intervention with antiretroviral therapy (ART) enables the modulation of HIV virus load and hence provides a unique opportunity to study the consequences of varying antigen load on the phenotype of virus-specific CD8(+) T lymphocytes in a persistent human viral infection. The recent advent of tetrameric peptide / HLA class I complexes has enabled the direct phenotypic characterization of antigen-specific T cell populations ex vivo. Here, we use this technology to examine directly ex vivo the consequences of therapeutic manipulation of HIV virus load on the phenotype of HIV-specific CTL. Our observations show that: (1) distinct sequential activation patterns of CD8(+) T cells are associated with increasing virus load; (2) T cell receptor (TCR) down-regulation without apoptosis represents an early event during the generation of a T cell response in a natural infection and precedes the emergence of two distinct antigen-specific CD8(+) T cell populations which differ in TCR and CD8 expression levels. Clear differences in surface Annexin V staining were observed between these populations. The observation that CTL activation, demonstrated by TCR and CD8 down-regulation, in response to rising levels of virus load, co-segregates with apoptosis only during later stages of the response indicates that antigen-associated cell death is restricted to distinct subpopulations of CTL.

Direct ex vivo analysis reveals distinct phenotypic patterns of HIV-specific CD8(+) T lymphocyte activation in response to therapeutic manipulation of virus load

Therapeutic intervention with antiretroviral therapy (ART) enables the modulation of HIV virus load and hence provides a unique opportunity to study the consequences of varying antigen load on the phenotype of virus-specific CD8(+) T lymphocytes in a persistent human viral infection. The recent advent of tetrameric peptide / HLA class I complexes has enabled the direct phenotypic characterization of antigen-specific T cell populations ex vivo. Here, we use this technology to examine directly ex vivo the consequences of therapeutic manipulation of HIV virus load on the phenotype of HIV-specific CTL. Our observations show that: (1) distinct sequential activation patterns of CD8(+) T cells are associated with increasing virus load; (2) T cell receptor (TCR) down-regulation without apoptosis represents an early event during the generation of a T cell response in a natural infection and precedes the emergence of two distinct antigen-specific CD8(+) T cell populations which differ in TCR and CD8 expression levels. Clear differences in surface Annexin V staining were observed between these populations. The observation that CTL activation, demonstrated by TCR and CD8 down-regulation, in response to rising levels of virus load, co-segregates with apoptosis only during later stages of the response indicates that antigen-associated cell death is restricted to distinct subpopulations of CTL.

The changing pattern of AIDS-defining illnesses with the introduction of highly active antiretroviral therapy (HAART)in a London clinic

OBJECTIVES

To quantify the progressive impact of combination antiretroviral therapy (ART) on the incidence of AIDS-defining illnesses (ADIs) over a 9-year period.

METHODS

Retrospective cohort study. Eligible patients were 1538 AIDS-free, HIV-1-positive patients attending a large HIV clinic in west London who were at risk of developing AIDS because their CD4 count had declined to < or =350 x 10(6)/l cells during the period 1 January 1990 and 31 December 1998. Incidence rates for the 12 most frequent ADIs were compared for two time periods, 1990-1995 (pre-HAART) and 1996-1998 (post-HAART), using Poisson regression methods. Multivariate Poisson regression models were used to examine the contribution of ART and HAART to any observed temporal trends in incidence rates.

RESULTS

After a median follow-up of 35 months, 450 (29%) patients had developed AIDS. Between the two time periods there was a significant decrease in the incidence of Pneumocystis carinii pneumonia (PCP) by 35% (4.11 per 100 person-years in 1990-1995 vs. 2.67 in 1996-1998;P= 0.007), Kaposi's sarcoma by 34% (3.27 vs. 2.17;P= 0.022) and cryptosporidiosis by 60% (0.76 vs. 0.31;P= 0.029). A non-significant reduction in incidence was observed for cryptococcosis by 45% (0.81 vs. 0.45;P= 0.11), oesophageal candidiasis by 29% (3.34 vs. 2.39;P= 0.053) and mycobacterium avium complex by 18% (1.58 vs. 1.29;P= 0.4), and a non-significant increase was observed for tuberculosis by 17% (0.62 vs. 0.73;P= 0.66) and non-Hodgkins lymphoma (NHL) by 51% (0.43 vs. 0.65;P= 0.31). The incidence of cerebral toxoplasmosis, cytomegalovirus, recurrent bacterial chest infections and dementia remained stable. There was a clear stepwise reduction in the incidence of PCP, Kaposi's sarcoma and cryptosporidiosis with the use of non-H AART and HAART regimens relative to no ART. In a multivariate analysis, the use of ART and HAART explained the progressive decrease in incidence of PCP and Kaposi's sarcoma.

CONCLUSIONS

The incidence of most ADIs has decreased over the last 9 years. The striking reduction in the inci-dence of PCP and Kaposi's sarcoma since 1996 can be attributed to the use of combination ART and particularly HAART. The non-significant increase in the incidence of NHL and tuberculosis needs confirmation in other patient cohorts.

The relationship of psychological variables and disease progression among long-term HIV-infected men

This study investigated the contribution of psychological factors to disease progression among long-term HIV-1 infected gay men. Participants completed self-report measures including coping strategies, life events, social support, personality and psychological morbidity and were followed clinically for up to 30 months. Cox proportional hazards survival analyses were carried out to CD4<200 x 106/1 and AIDS-related complex (ARC) or AIDS diagnosis controlling for viral load, antiretroviral drug use and CD4 count. Only acceptance coping was a significant predictor of time to ARC or AIDS diagnosis: the risk of ARC or AIDS was almost 5 times greater for those scoring within the lowest tertile compared with those scoring in the highest tertile (HR=4.7, 95% CI 1.8-12.3).

How generalizable are the results of large randomized controlled trials of antiretroviral therapy?

OBJECTIVES

To examine the generalizability of two large randomized controlled clinical trials of antiretroviral therapy in HIV-infected individuals.

METHODS

The demographic, clinical and laboratory characteristics of HIV-infected participants in two antiretroviral trials (Concorde and Delta) at three study sites were compared with those of two other groups of patients to whom the trial results would be applicable: eligible patients who were screened for the trials but who did not enrol, and eligible patients who were not approached or screened for the trials.

RESULTS

Among enrolled participants in the Concorde and Delta trials there was an under-representation of patients who had acquired HIV infection heterosexually (P = 0.014) or through injecting drug use (P = 0.03), and a greater representation of homosexual men (P < 0.001) compared to non-enrolled participants. Trial participants in Concorde had significantly less advanced immunosuppression compared to non-trial participants (P = 0.0001), while in Delta the converse was true. Concorde participants were also much less likely to be lost to follow-up for more than a year (9%) compared to eligible but unscreened patients (40%) (P < 0.001), and screened but unenrolled patients (22%) (P = 0.035).

CONCLUSIONS

In applying the findings of large randomized clinical trials, it is important to establish whether there are systematic differences between the characteristics of trial participants and eligible non-participants, which might affect the generalizability of the study results. A log of the characteristics of enrolled as well as eligible but non-enrolled patients should be maintained so that the representativeness of the trial population can be evaluated.

Ten-year trends in CD4 cell counts at HIV and AIDS diagnosis in a London HIV clinic

OBJECTIVE

To examine temporal trends (1986-1996) in the CD4 cell count at first HIV-1 positive test and initial AIDS diagnosis, and the influence of selected patient characteristics and treatment factors on these trends.

DESIGN

A retrospective clinic-based study.

SETTING

Three hospital-based clinics in West London.

PATIENTS

A group of 5921 adult HIV-1-seropositive persons and 2835 reported patients with AIDS over a 10-year period from 1 January 1986 to 1 October 1996.

METHODS

The CD4 cell count at HIV diagnosis (CD4HIV) was defined as the nearest CD4 cell count to within 2 months of HIV diagnosis; and the CD4 cell count at AIDS diagnosis (CD4AIDS) as the last CD4 cell count in the two months prior to the development of AIDS. Simple and multiple linear regression analysis were used to examine the influence of selected covariates on CD4HIV and CD4AIDS.

RESULTS

The percentage of patients with an available CD4HIV and CD4AIDS increased from less than 5% in 1987 to 53% and 40%, respectively, in 1990, and 79% and 48%, respectively, in 1996. Patients with a missing CD4HIV or CD4AIDS were younger and less likely to have received antiretroviral therapy or prophylaxis for Pneumocystis carinii pneumonia (PCP). There was no significant change in CD4HIV over a 10-year period (median 334 x 10(6) cells/l), but a lower CD4HIV was associated with older age at presentation and injecting drug use. There was a delay in the onset of clinical AIDS, with a fall in the median CD4AIDS value from 99 x 10(6) cells/l prior to 1987, to 58 x 10(6) cells/l in 1990, 68 x 10(6) cells/l in 1994 and 60 x 10(6) cells/l in 1996; this decline in onset was seen for PCP as well as for cytomegalovirus and atypical mycobacterial infections. At all time periods, a lower CD4AIDS was associated with combined use of antiretroviral therapy and PCP prophylaxis. After adjustment for use of antiretroviral therapy and PCP prophylaxis prior to AIDS diagnosis, year of diagnosis was no longer associated with CD4AIDS. There was a significant trend towards an improved survival following AIDS diagnosis from 20.1 months prior to 1988, to 20.3 months (1989-1990), 21.0 months (1991-1992) and 22.1 (1993-1994) (P < 0.0005).

CONCLUSIONS

The observed decline in CD4AIDS value was related to the introduction of antiretroviral therapy in 1988, and PCP prophylaxis in 1989. Temporal changes in the CD4 cell count at HIV and AIDS diagnosis among different demographic groups can provide insights into the changing natural history of the HIV epidemic and access to medical care. We recommend monitoring of the CD4 cell count at new HIV and AIDS diagnosis and at initiation of antiretroviral therapy as additional measures in national HIV/AIDS surveillance.

Early highly active antiretroviral therapy for acute HIV-1 infection preserves immune function of CD8+ and CD4+ T lymphocytes

Highly active antiretroviral therapy (HAART) has been advocated for the management of primary HIV-1 infection without clear understanding of its immunological effects. Here, we demonstrate that early use of HAART during primary infection preserves HIV-specific CD8(+) T cells physically and functionally while HIV-specific T cell help is sustained. We also show that even transient administration of HAART at seroconversion can preserve HIV-specific immunity. In contrast, delayed initiation of HAART is associated with a progressive loss of HIV-specific CD8(+) T cells and absent HIV-specific T cell help. These results imply that HIV-specific T help is damaged during primary HIV-1 infection. Early drug treatment, which preserves this immunity, also preserves HIV-specific CD8(+) T cells. These results have implications for understanding the early pathogenesis of HIV-1 infection and suggest that acute HIV infection should be treated aggressively and as early as possible.

Mycoplasma species in rapid and slow HIV progressors

We determined the relationship between the presence of Mycoplasma fermentans and Mycoplasma penetrans and the rate of progression of HIV-associated disease in a nested case-control study based on a cohort of 159 HIV-infected patients with different rates of disease progression. Study participants were divided into 3 progression groups: non-progressors who had been HIV-1 seropositive for at least 9 years and had remained asymptomatic with a CD4 cell count of > 500/mm3; slow progressors who had been HIV-1 seropositive for at least 9 years and whose CD4 cell count had fallen below 500 cells, and who had developed symptomatic disease or AIDS; and rapid progressors who had developed AIDS within 5 years of HIV infection. Peripheral blood mononuclear cells (PBMCs) were collected at enrollment and examined by mycoplasma polymerase chain reaction (PCR) assays. Three (7%) of 46 non-progressors, 3 (3%) of 86 slow progressors, and 2 (7%) of 27 rapid progressors were M. fermentans positive. The PBMCs from 91 subjects were tested for M. penetrans DNA and none was positive. The small proportion of M. fermentans-positive patients indicates that the mycoplasma cannot be important in the development of AIDS in the large majority of patients. Furthermore, no association was found between its presence and more rapid HIV disease progression.

Cytotoxic T lymphocytes and viral evolution in primary HIV-1 infection

Efforts to develop immune-based therapies for HIV infection have been impeded by incomplete definition of the immunological correlates of protection. Despite many precedents demonstrating that CD8(+) cytotoxic T lymphocytes are key mediators of protective anti-viral immunity in non-human animal models, direct evidence that these effector cells control viral replication in HIV-1 infection has remained elusive. The first part of this paper describes a detailed immunological and genetic study founded on evolutionary considerations. Following infection with HIV-1, virus variants which escaped recognition by autologous cytotoxic T lymphocytes were shown to possess a selection advantage within the host environment. Cytotoxic T lymphocytes therefore exert anti-viral pressure in vivo. This observation provides compelling evidence that cytotoxic T lymphocytes comprise a significant element of anti-retroviral immunity. Subsequently, the quantification of peripheral cytotoxic T lymphocyte frequencies utilizing peptide-(human leucocyte antigen class I) tetrameric complexes is described. Five patients with qualitatively similar immunodominant cytotoxic T lymphocyte responses during symptomatic primary HIV-1 infection were studied longitudinally. Expansions of virus-specific CD8(+) lymphocytes comprising up to 2% of the total CD8(+) T cell population were observed in the acute phase of infection. Antigenic load was identified as an important determinant of circulating HIV-1-specific CD8(+) lymphocyte levels; however, significant numbers of such cells were also found to persist following prolonged therapeutic suppression of plasma viraemia. In addition, an analysis of antigenic sequence variation with time in this case series suggests that the early administration of combination anti-retroviral therapy may limit HIV-1 mutational escape from host cytolytic specificities. The implications of these preliminary data are discussed. The data presented suggest that vaccination protocols should aim to elicit vigorous cytotoxic T lymphocyte responses to HIV-1. Attempts to stimulate polyvalent responses to mutationally intolerant epitopes are likely to be most effective. Optimal management of HIV-1 infection requires an understanding of dynamic host-virus interactions, and may involve strategies designed to enhance cytotoxic T lymphocyte activity following periods of anti-retroviral drug therapy.

Epidemiological features of drug resistant tuberculosis in Harare, 1994 to 1996

OBJECTIVES

To characterise the prevalence, clinical and radiological features of drug resistant tuberculosis in selected patients with pulmonary tuberculosis in Harare between 1994 and 1996.

DESIGN

A retrospective review of medical and microbiological records.

SETTING

Beatrice Road Infectious Diseases Hospital, Harare, Zimbabwe.

SUBJECTS

381 smear-positive tuberculosis patients who had samples submitted to the National Tuberculosis Reference Laboratory for culture and susceptibility testing.

MAIN OUTCOME MEASURES

Prevalence of resistance of isolated cultures of Mycobacterium tuberculosis to anti-tuberculosis drugs; clinical, radiological and microbiological response to treatment with recommended anti-tuberculosis regimens.

RESULTS

Resistance to one or more drugs was detected in 16 isolates (16/165, 9.7%), single drug resistance in five (3.0%) and resistance to two or more drugs in 11 (6.7%). There were no distinctive clinical or radiological features of drug-resistant tuberculosis, although a higher percent of drug resistant cases had evidence of pleural disease (25% vs 2.5%, p = 0.005). Neither past history of tuberculosis or known or suspected HIV infection was associated with the presence of drug resistance.

CONCLUSIONS

In spite of the resurgence of tuberculosis and the high prevalence of HIV infection in Zimbabwe, the rates of drug resistance have remained relatively low, even among a selected population at high risk of resistance. A significant proportion of cases of drug-resistant tuberculosis appear to be due to new transmission of drug resistant strains, which reinforces the importance of maintaining a surveillance system for the monitoring of drug susceptibility. Ongoing prospective studies should provide more reliable estimates of the prevalence and determinants of drug resistance in Zimbabwe.

Chemokine receptor polymorphisms and human immunodeficiency virus disease progression

The role of polymorphisms in genes encoding chemokines and their receptors (CCR2B, SDF-1, and the promoter region of CCR5) in human immunodeficiency virus (HIV) disease progression was studied in 132 white HIV type 1 (HIV-1)-infected participants from a United Kingdom cohort study. Genotyping was done by use of amplification refractory mutation system-polymerase chain reaction with sequence-specific primers, and Cox proportional hazards models were used to examine the impact of polymorphisms on time to a CD4 cell count <200x106/L and to CDC stage IV disease. The results confirm a significant association of the CCR2B-64I mutant genotype with slower progression to a CD4 count <200 (hazards ratio [HR], 0.39; 95% confidence interval [CI], 0.17-0.91) but not with the SDF-1alpha 3' UTR homozygous mutation. The effects of the CCR5 and CCR2 mutations were genetically independent and similar in the magnitude of their protective effect on progression to a CD4 count <200 cells. A novel finding was an association of borderline significance between homozygosity for C at nucleotide position 59353 in the CCR5 promoter region and a slower rate of CD4 cell decline to <200x106/L (HR, 0. 58; 95% CI, 0.34-0.996).

Acid-alcohol fast bacilli in sputa of HIV-infected patients

We identified 34 HIV-infected patients with sputum smear positive for acid-alcohol fast bacilli (AAFB) to determine any factors predictive of subsequent species identification. There were 20 cases of Mycobacterium tuberculosis (MTB), 9 cases of Mycobacterium avium-intracellulare (MAI), 3 cases of Mycobacterium kansasii and one each of Mycobacterium malmoense and Mycobacterium fortuitum. Factors associated with isolation of MAI were lower CD4 cell count, a higher incidence of previous AIDS diagnosis, a history of dyspnoea and a normal chest X-ray. The organism was isolated from blood cultures in 58% of patients with MTB and 78% of patients with MAI infection. Disseminated disease was diagnosed in 45% of MTB patients and 33% of MAI patients.

Sequence variations in human immunodeficiency virus type 1 Nef are associated with different stages of disease

nef alleles derived from a large number of individuals infected with human immunodeficiency virus type 1 (HIV-1) were analyzed to investigate the frequency of disrupted nef genes and to elucidate whether specific amino acid substitutions in Nef are associated with different stages of disease. We confirm that deletions or gross abnormalities in nef are rarely present. However, a comparison of Nef consensus sequences derived from 41 long-term nonprogressors and from 50 individuals with progressive HIV-1 infection revealed that specific variations are associated with different stages of infection. Five amino acid variations in Nef (T15, N51, H102, L170, and E182) were more frequently observed among nonprogressors, while nine features (an additional N-terminal PxxP motif, A15, R39, T51, T157, C163, N169, Q170, and M182) were more frequently found in progressors. Strong correlations between the frequency of these variations in Nef and both the CD4(+)-cell count and the viral load were observed. Moreover, analysis of sequential samples obtained from two progressors revealed that several variations in Nef, which were more commonly observed in patients with low CD4(+)-T-cell counts, were detected only during or after progression to immunodeficiency. Our results indicate that sequence variations in Nef are associated with different stages of HIV-1 infection and suggest a link between nef gene function and the immune status of the infected individual.

Are HIV-infected patients with rapid CD4 cell decline a subgroup who benefit from early antiretroviral therapy?

We have developed a model to determine whether asymptomatic HIV-infected individuals who have a rapid CD4 cell decline are a subgroup who might benefit from early antiretroviral therapy. Data were obtained from a subgroup of participants in the Concorde and EACG020 trials, two randomized, double-blind, comparative trials of immediate (IMM) versus deferred (DEF) zidovudine therapy in asymptomatic HIV-infected individuals. The subgroup comprised 297 patients (IMM = 154, DEF = 143) who had at least one CD4 cell count before and after randomization. The median CD4 cell count at randomization was 491 x 10(6)/L, and the median follow-up was 61 months. The rate of CD4 decline before and after randomization was estimated using multi-level linear regression analysis, and patients were stratified into quartiles according to the rate of CD4 cell decline before randomization. Outcome measures were the development of AIDS, a 50% drop in CD4 count from the baseline, and death. A Cox proportional hazards model was used to examine whether the effect of zidovudine on disease progression varied according to the previous rate of CD4 decline. We found that a more rapid rate of CD4 decline before randomization was associated with a greater reduction in the rate of CD4 decline following IMM antiretroviral therapy (r = -0.5, P = 0.03). The greatest risk reduction in disease progression with IMM antiretroviral therapy was seen in the quartile of patients with the highest rate of CD4 decline (> or = 26 x 10(6) cells/L per 6 months) (hazards ratio (HR) = 0.61, 95% CI = 0.35-1.05). However, this effect was statistically significant in only the Concorde trial (HR = 0.48, 95% CI = 0.29-0.89). In contrast, we found no evidence in the EACG020 trial of any trend towards greater benefit in those with the most rapid CD4 cell decline. These findings suggest that asymptomatic patients with rapid CD4 cell decline are a subgroup likely to benefit from early antiretroviral therapy. This analytic approach should now be replicated in trials of combination therapy, and these should include viral load data.

Association between a defective CCR-5 gene and progression to disease in HIV infection

We measured the effect(s) of CCR-5 genotype on disease progression by studying the frequency of a defective CCR-5 delta32 allele within a cohort of long-term infected individuals. An elevated frequency of CCR-5 delta32 heterozygotes within the cohort compared with a control population of blood donors was observed. An association between progression rate and CCR-5 delta32 heterozygosity was observed. Furthermore, analysis of proviral DNA V3 sequences from a subset of the cohort predicted that the majority of individuals (39 of 44) were infected with viruses predicted to utilize the beta-chemokine receptor CCR-5. The marked association between CCR-5 genotype and disease progression observed in this study may be a consequence of the predicted low frequency of CXCR-4-utilizing viruses present within the selected cohort.

HLA-Cw*0602 and HIV-associated psoriasis

The aetiopathogenesis of psoriasis is unknown, but genetic and environmental factors may be involved. Psoriasis may not be one disease but a cutaneous inflammatory reaction pattern consequent upon several different independent or related stimuli in susceptible individuals. There are controversial issues regarding the immunological basis of psoriasis and the role of CD4 vs. CD8 T lymphocytes. Psoriasis has been associated with HLA-Cw6 and Cw7 by serology and specifically with HLA-Cw*0602 by polymerase chain reaction (PCR) typing. Psoriasis is probably no more common in HIV infection than in the general population; however, it may appear for the first time or pre-existing psoriasis may worsen and be difficult to treat in HIV disease. We have investigated the prevalence of HLA-C alleles, in the specific clinical context of HIV infection complicated by type 1 psoriasis, in a case control study of 14 men with HIV disease and type 1 psoriasis and 147 HIV-infected patients without psoriasis. Typing was performed using PCR with sequence-specific amplification primers. Eleven of 14 patients (79%) with psoriasis carried the HLA-Cw*0602 allele compared with 24.5% of those without psoriasis (odds ratio = 11.31; 95% confidence limits 2. 73 to 65.36; P = 0.0001). Two patients without the HLA-Cw*0602 allele carried instead the closely related Cw*0401/3 allele. The results confirm the previously reported association between the HLA-Cw*0602 allele and type 1 psoriasis, and suggest that the association with HLA-Cw*0602 is stronger in HIV-associated psoriasis although this trend needs to be supported by a larger sample. The immunodysregulation resulting from HIV infection may trigger psoriasis in those genetically predisposed by the Cw*0602 allele. As CD8 T cells recognize antigens in the context of class I major histocompatibility complex, the identification of an HLA class I association in HIV-associated psoriasis strengthens the argument for an important role for CD8 + T lymphocytes in the immunopathogenesis of psoriasis. Investigations of the pathogenesis of psoriasis should take account of clinical and other subtypes already identified.

Bronchopulmonary Kaposi's sarcoma in 106 HIV-1 infected patients

The objectives of this study were to describe the clinical and radiological features at presentation, and the natural history of HIV-related bronchopulmonary Kaposi's sarcoma. A retrospective review of medical records and chest radiographs was performed in 106 HIV-infected homosexual men with bronchopulmonary Kaposi's sarcoma diagnosed at bronchoscopy between September 1988 and November 1994. The majority of patients had evidence of advanced HIV disease at diagnosis (median CD4 cell count was 15 x 10(6)/l, range 0-288), and 93% had had a diagnosis of cutaneous Kaposi's sarcoma for a median duration of 11 months prior to diagnosis of their bronchopulmonary disease. The most frequent symptoms at presentation were cough (92%), dyspnoea (69%), pleuritic pain (20%), haemoptysis (13%) and wheezing (10%). The most common radiological finding in 73% of our series was of poorly defined and confluent opacities, with predominant middle and lower zone involvement. Median survival was 4 months (range 0-37 months) from diagnosis and 9 months (range 1-25) from the onset of symptoms. Treatment with either chemotherapy or radiotherapy was associated with a significantly reduced risk of death (hazards ratio (HR)=0.48, 95% CI=0.26-0.87). Factors associated with a poor survival, after adjustment for treatment effect were older age (HR=1.79, 95% CI=1.22-2.84) for each 10-year increase in age; a history of pleuritic pain (HR=2.97, 95% CI=1.39-6.32); presence of pleural effusion on X-ray (HR=2.01, 95% CI=1.13-3.59) and a prior diagnosis of cutaneous Kaposi's sarcoma (HR=1.8, 95% CI=1.00, 3.24). Bronchopulmonary Kaposi's sarcoma occurs mainly in patients with advanced HIV disease and a prior history of cutaneous disease. Survival is poor, and adverse prognostic factors include older age at diagnosis and the presence of pleural disease.

1H MR spectroscopy of the brain in HIV-1-seropositive subjects: evidence for diffuse metabolic abnormalities

PURPOSE

To analyze brain metabolite changes in HIV-1-seropositive subjects in order to define whether the neuronal impairment is a localized or more diffuse process.

MATERIALS AND METHODS

15 patients and 18 volunteers underwent multivoxel proton magnetic resonance (MR) spectroscopy at 1.5T. Nine patients were classified as being neuropsychiatrically unimpaired and six as having HIV-1-associated dementia on the basis of a full neuropsychological examination. Spectra were analysed from multiple voxels located in the fronto-parietal cortex and white matter at the level of centrum semiovale.

RESULTS

A significant reduction in mean peak area ratios of NAA/Cr (p<0.005 in the grey matter, p<0.01 in the white matter) and an elevation in mean Cho/Cr (p<0.005 in both grey matter and white matter) were observed in patients with HIV-1-associated dementia when compared to healthy volunteers. No significant metabolite abnormalities were detected in the neuropsychiatrically unimpaired group, although there was a similar trend in the metabolite ratios. The changes in metabolite ratios were of the same order of magnitude in the cortical grey matter and subcortical white matter as in the deeper white matter in all patients. There were also no significant regional variations in mean metabolite ratios between right and left hemispheres or anterior and posterior voxels at the level of the brain studied. There were no abnormalities in Glx/Cr in any spectra analysed from either patient group.

CONCLUSION

The absence of significant regional variation in metabolite ratios at the level of the centrum semiovale provides some evidence that abnormalities of cerebral metabolites in HIV-infected patients may be part of a diffuse process.

Research potentials and pitfalls in the use of an HIV clinical database: Chelsea and Westminster Hospital

This article summarizes the various problems and pitfalls in using clinical databases for epidemiologic research, with particular reference to an HIV clinical database. The combined population of HIV-infected individuals attending the Chelsea and Westminster Hospital, the Charing Cross Hospital, and the Victoria Clinic in London is the largest cohort of HIV-positive individuals in the U.K. A computerized database was developed in the mid-1980s and was adapted into a clinically oriented observational database for approximately 6,653 HIV-1-positive registered patients from three hospital-based clinics within the Riverside Health Authority in London, U.K.: Chelsea and Westminster Hospital Clinic (n = 5,000); Charing Cross Hospital (n = 500); and the Victoria Clinic (n = 500). The majority (83%) of HIV-infected patients registered at these sites are homosexual or bisexual men. Of 2,078 patients seen within the last 6 months, 22% are asymptomatic and 33% have AIDS; 30% have a CD4 cell count of less than 100 cells/mm3 and 17% have a CD4 cell count of greater than 500 cells/mm3. Dates of seroconversion are known for approximately 285 patients. For each patient, information on demographic characteristics, clinical symptoms, and HIV-related diagnoses, outpatient pharmacy prescriptions, day care treatments and procedures, and enrollment into clinical trials is routinely collected at outpatient clinic visits and entered into the database. Inpatient diagnoses and treatments were integrated into the database in September 1995. Unused serum samples from routine AIDS antibody or antigen testing are stored in a local specimen repository. The main purpose of the HIV database is to provide a multipurpose resource for use by physicians, researchers, and managers for administration, clinical care, and research. The specific functions of the database are the following: to enhance patient management by providing access to a clinical summary sheet detailing up-to-date information; to serve as a research tool for clinical and epidemiologic research; to aid in the identification of patients eligible for planned or ongoing clinical trials; to provide a facility for local and regional AIDS surveillance and reporting; and to provide a facility for administration and resource management of HIV services. The major limitations of this database in the conduct of clinical research have been losses to follow-up and incomplete information about clinical outcomes, because physicians have failed to update the clinical information.

Neutralization of primary and T-cell line adapted isolates of human immunodeficiency virus type 1: role of V3-specific antibodies

The role of the third variable domain (V3) of gp120 in the neutralization of primary and T-cell line adapted (TCLA) strains of human immunodeficiency virus type 1 (HIV-1) by serum from HIV-1-infected individuals was investigated. A primary virus isolate, M2424/4, when adapted to H9 cells, was more sensitive to neutralization on MT2 cells than the same stock passaged in PBMC. Neutralization of the PBMC-passaged stock by V3-specific MAbs was abrogated by addition of V3 (MN) peptide. However, exogenous V3 (MN) peptide failed to reduce the neutralization of this isolate on PBMC, or MT2 cells, by high titre anti-HIV-1 polyclonal human sera in contrast to the extensive reduction of neutralization by the same sera on MT2 cells using the prototype MN strain (4- to > or = 24-fold) and the TCLA M2424/H9 isolate (2- to 8-fold). These results indicate that the neutralization of primary virus isolates by serum from HIV-1-infected individuals is not significantly mediated by V3-specific antibodies.

Relationship between CD4 count and CD4% in HIV-infected people

OBJECTIVE

To describe the relationship between absolute CD4 count and CD4%, and the influence on this of gender, risk group, age, a diagnosis of AIDS, use of zidovudine (ZDV) therapy and PCP prophylaxis.

METHODS

9203 paired serial measurements of CD4 count and CD4% on 1017 initially AIDS-free and ZDV-naive HIV positive patients from a London-based cohort were available for analysis. Multi-level regression procedures were used on log-transformed data to relate values of CD4 count to a given level of CD4%. We estimated the effect of selected covariates on this relationship from the exponent of the covariate coefficient.

RESULTS

A strong linear relationship was found between log CD4 and log CD4%, CD4 = e 1.78(CD4%)1.26 or 5.93 (CD4%)1.26 (excluding covariates). Based on this model, a CD4% of 5%, 15%, and 30% corresponded to an estimated CD4 count (95% confidence interval [CI]) of 45 cells/mm3 (17-117 cells/mm3), 182 cells/mm3 (64-499 cells/mm3) and 438 cells/mm3 (132-1395 cells/mm3), respectively. However, after adjustment for selected covariates, the predicted CD4 count for a given CD4% was found to be lower among heterosexuals and injecting drug users as compared with homosexual men by 30% and 17% respectively; following an AIDS diagnosis by 21%; and after initiation of ZDV therapy and PCP prophylaxis by 19% and 10%, respectively.

CONCLUSION

This analysis should be useful to clinicians and researchers in relating values of CD4 count to CD4%, although we have demonstrated that this is not a simple relationship. The wide CI observed in the estimated CD4 count particularly at high CD4% values, and the adjustments necessary according to risk group, following an AIDS diagnosis and use of ZDV and PCP therapy limit its application in the clinical setting.

CD4 cell counts of 200 x 10(6)/1 or below in natural history studies and surveillance: is one enough or are two better?

A retrospective cohort study was performed to examine the extent and clinical significance of misclassification associated with using the current United States AIDS case defining category of an initial CD4 count < or = 200 cells x 10(6)/l (< or = 200) compared with a definition requiring two consecutive counts below this level. The main outcomes examined were the probability of subsequent CD4 counts > 200 x 10(6)/l (> 200) and progression times to AIDS and death. Of the 2025 predominantly male homosexual HIV-positive patients attending two hospital based HIV clinics with initial CD4 cell counts < or = 200, 1524 (75%) subsequently had consecutive counts < or = 200, but only half did so at the next CD4 count. Ten per cent had either no further or only non-consecutive counts < or = 200, and 15% had only one CD4 count available for analysis. The cumulative proportion of patients with a CD4 count > 200 at one year after a first count of < or = 200 was about twice (39%) that observed among the subgroup with at least two consecutive counts < or = 200 (19%). The times from the initial counts of < or = 200 to AIDS and death were also shorter by six months and two months, respectively, in the subgroup with two or more consecutive counts < or = 200. A significant proportion of patients will be prematurely classified as having a CD4 cell count < or = 200 if a single CD4 count below this level is accepted. A definition of two consecutive counts < or = 200 should be adopted in preference to a single count < or = 200 for natural history studies and clinical trials, in which precise estimates of the time to or from a defined CD4 threshold are important. In surveillance programmes, however, such an approach may be impractical because of missing or infrequent serial CD4 counts, although adjustments can be made based on these estimates of premature misclassification.

Positive selection of HIV-1 cytotoxic T lymphocyte escape variants during primary infection

Cytotoxic T lymphocytes (CTLs) are thought to play a crucial role in the termination of the acute primary HIV-1 syndrome, but clear evidence for this presumption has been lacking. Here we demonstrate positive selection of HIV-1 proviral sequences encoding variants within a CTL epitope in Nef, a gene product critical for viral pathogenicity, during and after seroconversion. These positively selected HIV-1 variants carried epitope sequence changes that either diminished or escaped CTL recognition. Other proviruses had mutations that abolished the Nef epitope altogether. These results provide clear evidence that CTLs exert selection pressure on the viral population in acute HIV-1 infection.

Long-term survival in patients with advanced immunodeficiency

OBJECTIVE

To identity prognostic factors associated with survival time in HIV-infected patients with advanced immunodeficiency.

DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 1284 HIV-infected patients with serial CD4 count measurements and at least one CD4 cell count < or = 50 x 10(6)/I (CD4 < or = 50).

MAIN OUTCOME MEASURE

Survival from initial CD4 cell count < or = 50 x 10(6)/l.

RESULTS

The median survival from initial CD4 < or = 50 x 10(6)/l was 17.1 months. The risk of death increased by 2% 195% confidence interval (Cl), 1-31 for each year of age, by 10% (95% Cl, 3-16) for each 10 x 10(6)/l decrease in CD4 count, and by 14% (95% Cl, 9-18) for each 1 g/dl decrease in haemoglobin level. Compared to AIDS-free patients with CD4 < or = 50 x 10(6) cells/l, the risk of dying was 1.5-fold (95% Cl, 1.2-1.9) that of patients who had an AIDS diagnosis for fewer than 3 months prior to CD4 < or = 50, 1.8-fold for patients with an AIDS diagnosis for 4-11 months prior to CD4 < or = 50, and twice that of patients with AIDS for > or = 12 months prior to CD4 < or = 50. The risk of dying for patients whose rate of CD4 cell decline was > 40 x 10(6)/l per 6 months was 1.7-fold (95% Cl, 1.3-2.3) that of patients with an average CD4 cell loss < 40 x 10(6)/l per 6 months, after adjusting for age, haemoglobin and duration of AIDS prior to CD4 < or = 50 x 10(6) cells/l. A prognostic score was developed from the final multivariate model, based on age at CD4 < or = 50, haemoglobin at CD4 < or = 50, duration of AIDS and rate of CD4 decline prior to CD4 < or = 50.

CONCLUSIONS

Routinely available clinical and laboratory data including haemoglobin level, rate of CD4 decline and duration of AIDS can be readily translated into a prognostic score and then used to predict the survival experience of an HIV-infected patient with advanced immunodeficiency.