Projecting the impact of multi-cancer early detection on late-stage incidence using multi-state disease modeling

BACKGROUND

Downstaging- reduction in late-stage incidence-has been proposed as an endpoint in randomized trials of multi-cancer early detection (MCED) tests. How downstaging depends on test performance and follow-up has been studied for some cancers but is understudied for cancers without existing screening and for MCED tests that include these cancer types.

METHODS

We develop a model for cancer natural history that can be fit to registry incidence patterns under minimal inputs and can be estimated for solid cancers without existing screening. Fitted models are combined to project downstaging in MCED trials given sensitivity for early- and late-stage cancers. We fit models for 12 cancers using incidence data from the Surveillance, Epidemiology, and End Results program and project downstaging in a simulated trial under variable preclinical latencies and test sensitivities.

RESULTS

A proof-of-principle lung cancer model approximated downstaging in the National Lung Screening Trial. Given published stage-specific sensitivities for 12 cancers, we projected downstaging ranging 21%-43% across plausible preclinical latencies in a hypothetical 3-screen MCED trial. Late-stage incidence reductions manifest soon after screening begins. Downstaging increases with longer early-stage latency or higher early-stage test sensitivity.

CONCLUSION

Even short-term MCED trials could produce substantial downstaging given adequate early-stage test sensitivity.

IMPACT

Modeling the natural histories of cancers without existing screening facilitates analysis of novel MCED products and trial designs. The framework informs expectations of MCED impact on disease stage at diagnosis and could serve as a building block for designing trials with late-stage incidence as the primary endpoint.

Racial disparities in prostate cancer mortality: a model-based decomposition of contributing factors

To investigate the relative contributions of natural history and clinical interventions to racial disparities in prostate cancer mortality in the United States, we extended a model that was previously calibrated to Surveillance, Epidemiology, and End Results (SEER) incidence rates for the general population and for Black men. The extended model integrated SEER data on curative treatment frequencies and cancer-specific survival. Starting with the model for all men, we replaced up to 9 components with corresponding components for Black men, projecting age-standardized mortality rates for ages 40-84 years at each step. Based on projections in 2019, the increased frequency of developing disease, more aggressive tumor features, and worse cancer-specific survival in Black men diagnosed at local-regional and distant stages explained 38%, 34%, 22%, and 8% of the modeled disparity in mortality. Our results point to intensified screening and improved care in Black men as priority areas to achieve greater equity.

Abstract P4-03-03: Elevated Risk of Breast Cancer Diagnosis in Women with Dense Breasts reflects a similarly Elevated Risk of Breast Cancer Onset that is Robust to the Effect of Density on Mammography Sensitivity

Dense breasts are associated with a higher risk of breast cancer diagnosis, which has impacted risk prediction tools and patient notification policies. However, given that mammography is less sensitive for women with dense breasts and these women may be subject to different confirmation testing pathways, the true association between breast density and cancer risk is unknown. We investigated the relationship between breast density and onset using a natural history model that accounts for differential sensitivity and rates of exams by breast density. Data consisted of Breast Cancer Surveillance Consortium mammogram and cancer outcomes among women aged 40-54 with a first digital mammogram between 2000-2018 (N=33,542). Of these, 15,092 had non-dense (almost entirely fatty or scattered fibroglandular densities) and18,450 had dense (heterogeneously dense or extremely dense) breasts. We estimated the empirical sensitivity of mammograms in dense and non-dense breasts (fraction of diagnosed cancers that were screen detected) and examined rates of mammograms by density. We estimated the relative risk of breast cancer diagnosis five years after the first exam using Kaplan Meier methods and the relative risk of breast cancer onset from a natural history model, assuming density-specific sensitivity was equal to the empirical sensitivity. Empirical sensitivity was .88 in women with non-dense and .78 in women with dense breasts. Mammogram utilization was somewhat higher in women with dense breasts (HR for subsequent mammograms 1.10 (95% CI [1.07, 1.12]). The relative risk of diagnosis for dense versus non-dense breasts was 1.80 (95% CI [1.46,2.57]); based on the natural history model the relative risk of onset was 1.73 [1.43,2.25]. The estimated relative risk of onset ranged from 1.67 to 2.03 under assumptions that the relative sensitivity of the screening episode for dense versus non-dense breasts was 1.0 to 0.4. In conclusion, the association of risk of breast cancer onset with breast density is robust to assumptions about the relative sensitivity in dense and non-dense breasts.

Citation Format: Jane M. Lange, Charlotte Gard, Ellen O’meara, Ruth Etzioni. Elevated Risk of Breast Cancer Diagnosis in Women with Dense Breasts reflects a similarly Elevated Risk of Breast Cancer Onset that is Robust to the Effect of Density on Mammography Sensitivity [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-03-03.

Evaluation of Prostate Cancer Screening Strategies in a Low-Resource, High-risk Population in the Bahamas

Importance

The benefit of prostate-specific antigen screening may be greatest in high-risk populations, including men of African descent in the Caribbean. However, organized screening may not be sustainable in low- and middle-income countries.

Objective

To evaluate the expected population outcomes and resource use of conservative prostate-specific antigen screening programs in the Bahamas.

Design Setting and Participants

Prostate cancer incidence from GLOBOCAN and prostate-specific antigen screening data for 4300 men from the Bahamas were used to recalibrate 2 decision analytical models previously used to study prostate-specific antigen screening for Black men in the United States. Data on age and results obtained from prostate-specific antigen screening tests performed in Nassau from 2004 to 2018 and in Freeport from 2013 to 2018 were used. Data were analyzed from January 15, 2021, to March 23, 2022.

Interventions

One or 2 screenings for men aged 45 to 60 years and conservative criteria for biopsy (prostate-specific antigen level >10 ng/mL) and curative treatment (Gleason score ≥8) were modeled. Categories of Gleason scores were 6 or lower, 7, and 8 or higher, with higher scores indicating higher risk of cancer progression and death.

Main Outcomes and Measures

Projected numbers of tests and biopsies, prostate cancer (over)diagnoses, lives saved, and life-years gained owing to screening from 2022 to 2040.

Results

In this decision analytical modeling study, screening histories from 4300 men (median age, 54 years; range, 13-101 years) tested between 2004 and 2018 at 2 sites in the Bahamas were used to inform the models. Screening once at 60 years of age was projected to involve 40 000 to 42 000 tests (range between models) and prevent 500 to 600 of 10 000 to 14 000 prostate cancer deaths. Screening at 50 and 60 years doubled the number of tests but increased lives saved by only 15% to 16%. Among onetime strategies, screening once at 60 years of age involved the fewest tests per life saved (74-84 tests) and curative treatments per life saved (1.2-2.8 treatments).

Conclusions and Relevance

The findings of this decision analytical modeling study of prostate cancer screening in the Bahamas suggest that limited screening offered modest benefits that varied with screening ages and number of tests. The results can be combined with data on capacity constraints and evaluated relative to competing national public health priorities.

Lifetime Benefits and Harms of Prostate-Specific Antigen-Based Risk-Stratified Screening for Prostate Cancer

Background

Studies conducted in Swedish populations have shown that men with lowest prostate-specific antigen (PSA) levels at ages 44–50 years and 60 years have very low risk of future distant metastasis or death from prostate cancer. This study investigates benefits and harms of screening strategies stratified by PSA levels.

Methods

PSA levels and diagnosis patterns from two microsimulation models of prostate cancer progression, detection, and mortality were compared against results of the Malmö Preventive Project, which stored serum and tracked subsequent prostate cancer diagnoses for 25 years. The models predicted the harms (tests and overdiagnoses) and benefits (lives saved and life-years gained) of PSA-stratified screening strategies compared with biennial screening from age 45 years to age 69 years.

Results

Compared with biennial screening for ages 45–69 years, lengthening screening intervals for men with PSA less than 1.0 ng/mL at age 45 years led to 46.8–47.0% fewer tests (range between models), 0.9–2.1% fewer overdiagnoses, and 3.1–3.8% fewer lives saved. Stopping screening when PSA was less than 1.0 ng/mL at age 60 years and older led to 12.8–16.0% fewer tests, 5.0–24.0% fewer overdiagnoses, and 5.0–13.1% fewer lives saved. Differences in model results can be partially explained by differences in assumptions about the link between PSA growth and the risk of disease progression.

Conclusion

Relative to a biennial screening strategy, PSA-stratified screening strategies investigated in this study substantially reduced the testing burden and modestly reduced overdiagnosis while preserving most lives saved. Further research is needed to clarify the link between PSA growth and disease progression.

Prostate cancer mortality and metastasis under different biopsy frequencies in North American active surveillance cohorts

BACKGROUND

Active surveillance (AS) is an accepted means of managing low-risk prostate cancer. Because of the rarity of downstream events, data from existing AS cohorts cannot yet address how differences in surveillance intensity affect metastasis and mortality. This study projected the comparative benefits of different AS schedules in men diagnosed with prostate cancer who had Gleason score (GS) ≤6 disease and risk profiles similar to those in North American AS cohorts.

METHODS

Times of GS upgrading were simulated based on AS data from the University of Toronto, Johns Hopkins University, the University of California at San Francisco, and the Canary Pass Active Surveillance Cohort. Times to metastasis and prostate cancer death, informed by models from the Scandinavian Prostate Cancer Group 4 trial, were projected under biopsy surveillance schedules ranging from watchful waiting to annual biopsies. Outcomes included the risk of metastasis, the risk of death, remaining life-years (LYs), and quality-adjusted LYs.

RESULTS

Compared with watchful waiting, AS biopsies reduced the risk of prostate cancer metastasis and prostate cancer death at 20 years by 1.4% to 3.3% and 1.0% to 2.4%, respectively; and 5-year biopsies reduced the risk of metastasis and prostate cancer death by 1.0% to 2.4% and 0.6% to 1.6%, respectively. There was little difference between annual and 5-year biopsy schedules in terms of LYs (range of differences, 0.04-0.16 LYs) and quality-adjusted LYs (range of differences, -0.02 to 0.09 quality-adjusted LYs).

CONCLUSIONS

Among men diagnosed with GS ≤6 prostate cancer, obtaining a biopsy every 3 or 4 years appears to be an acceptable alternative to more frequent biopsies. Reducing surveillance intensity for those who have a low risk of progression reduces the number of biopsies while preserving the benefit of more frequent schedules.

ESTIMATING AND COMPARING CANCER PROGRESSION RISKS UNDER VARYING SURVEILLANCE PROTOCOLS

Outcomes after cancer diagnosis and treatment are often observed at discrete times via doctor-patient encounters or specialized diagnostic examinations. Despite their ubiquity as endpoints in cancer studies, such outcomes pose challenges for analysis. In particular, comparisons between studies or patient populations with different surveillance schema may be confounded by differences in visit frequencies. We present a statistical framework based on multistate and hidden Markov models that represents events on a continuous time scale given data with discrete observation times. To demonstrate this framework, we consider the problem of comparing risks of prostate cancer progression across multiple active surveillance cohorts with different surveillance frequencies. We show that the different surveillance schedules partially explain observed differences in the progression risks between cohorts. Our application permits the conclusion that differences in underlying cancer progression risks across cohorts persist after accounting for different surveillance frequencies.

A Framework for Treatment Decision Making at Prostate Cancer Recurrence

BACKGROUND

Of the 50,000 men in the US who elect for radical prostatectomy for prostate cancer, 24% to 40% will have a prostate-specific antigen (PSA) recurrence (PSA-R) within 10 years. Deciding whether to administer salvage therapy (ST) at PSA-R presents challenges, as treatment reduces the risk of progression to clinical metastasis but incurs unnecessary side effects should the man die before metastasis. We have developed a new harm-benefit framework using a clinical cohort to inform shared decision making between patients and physicians at PSA-R.

METHODS

Records of 1,045 Johns Hopkins University Hospital patients diagnosed between 1984 and 2013 who had PSA-R following radical prostatectomy were analyzed using marginal structural models to estimate the baseline risk of metastasis and the effect of ST (radiation therapy with or without hormone therapy) while accounting for selection into ST on the basis of PSA growth. The estimated model predicts the harm-benefit tradeoffs of ST within patient subgroups. The benefit of ST is the absolute reduction in the risk of metastasis within 10 years; the harm is the frequency of cancers that would not have metastasized in the patient's lifetime in the absence of ST (overtreatment).

RESULTS

The adjusted hazard ratio associated with ST was 0.41 (95% CI, 0.31 to 0.55). Providing ST to all men at PSA-R reduced the risk of metastasis from 43% to 23% but led to 31% of men being overtreated (harm/benefit = 31/(43-23) = 1.6). Providing ST to men with Gleason score >7 reduced the risk of metastasis from 67% to 39%, with 13% of men being overtreated (harm/benefit = 13/(67-39) = 0.5).

CONCLUSIONS

A quantitative framework that evaluates primary harms and benefits of ST after PSA-R will facilitate informed decision making. Immediate ST may be more appropriate in patient subgroups at elevated risk of metastasis.

Is the closest facility the one actually used? An assessment of travel time estimation based on mammography facilities

Background

Characterizing geographic access depends on a broad range of methods available to researchers and the healthcare context to which the method is applied. Globally, travel time is one frequently used measure of geographic access with known limitations associated with data availability. Specifically, due to lack of available utilization data, many travel time studies assume that patients use the closest facility. To examine this assumption, an example using mammography screening data, which is considered a geographically abundant health care service in the United States, is explored. This work makes an important methodological contribution to measuring access—which is a critical component of health care planning and equity almost everywhere.

Method

We analyzed one mammogram from each of 646,553 women participating in the US based Breast Cancer Surveillance Consortium for years 2005–2012. We geocoded each record to street level address data in order to calculate travel time to the closest and to the actually used mammography facility. Travel time between the closest and the actual facility used was explored by woman-level and facility characteristics.

Results

Only 35 % of women in the study population used their closest facility, but nearly three-quarters of women not using their closest facility used a facility within 5 min of the closest facility. Individuals that by-passed the closest facility tended to live in an urban core, within higher income neighborhoods, or in areas where the average travel times to work was longer. Those living in small towns or isolated rural areas had longer closer and actual median drive times.

Conclusion

Since the majority of US women accessed a facility within a few minutes of their closest facility this suggests that distance to the closest facility may serve as an adequate proxy for utilization studies of geographically abundant services like mammography in areas where the transportation networks are well established.

Breast cancer in female survivors of Wilms tumor: a report from the national Wilms tumor late effects study

BACKGROUND

The standard treatment of pulmonary metastases in patients with Wilms tumor (WT) includes 12-gray radiotherapy (RT) to the entire chest. To the authors' knowledge, the risk of breast cancer (BC) in a large cohort of female survivors of WT has not previously been reported.

METHODS

A total of 2492 female participants in National Wilms Tumor Studies 1 through 4 (1969-1995) were followed from age 15 years through the middle of 2013 for incident BC. The median age at the time of last contact was 27.3 years. The authors calculated cumulative risk at age 40 years (CR40), hazard ratios (HR) by Cox regression, standardized incidence ratios (SIRs) relative to US population rates, and 95% confidence intervals (95% CIs).

RESULTS

The numbers of survivors with invasive BC divided by the numbers at risk were 16 of 369 (CR40, 14.8% [95% CI, 8.7-24.5]) for women who received chest RT for metastatic WT, 10 of 894 (CR40, 3.1% [95% CI, 1.3-7.41]) for those who received only abdominal RT, and 2 of 1229 (CR40, 0.3% [95% CI, 0.0-2.3]) for those who received no RT. The SIRs for these 3 groups were 27.6 (95% CI, 16.1-44.2) based on 5010 person-years (PY) of follow-up, 6.0 (95% CI, 2.9-11.0) based on 13,185 PY of follow-up, and 2.2 (95% CI, 0.3-7.8) based on 13,560 PY of follow-up, respectively. The risk was high regardless of the use of chest RT among women diagnosed with WT at age ≥10 years, with 9 of 90 women developing BC (CR40, 13.5% [95% CI, 5.6-30.6]; SIR, 23.6 [95% CI, 10.8-44.8] [PY, 1463]).

CONCLUSIONS

Female survivors of WT who were treated with chest RT had a high risk of developing early BC, with nearly 15% developing invasive disease by age 40 years. Current guidelines that recommend screening only those survivors who received ≥20 Gy of RT to the chest might be reevaluated.

A joint model for multistate disease processes and random informative observation times, with applications to electronic medical records data

Multistate models are used to characterize individuals' natural histories through diseases with discrete states. Observational data resources based on electronic medical records pose new opportunities for studying such diseases. However, these data consist of observations of the process at discrete sampling times, which may either be pre-scheduled and non-informative, or symptom-driven and informative about an individual's underlying disease status. We have developed a novel joint observation and disease transition model for this setting. The disease process is modeled according to a latent continuous-time Markov chain; and the observation process, according to a Markov-modulated Poisson process with observation rates that depend on the individual's underlying disease status. The disease process is observed at a combination of informative and non-informative sampling times, with possible misclassification error. We demonstrate that the model is computationally tractable and devise an expectation-maximization algorithm for parameter estimation. Using simulated data, we show how estimates from our joint observation and disease transition model lead to less biased and more precise estimates of the disease rate parameters. We apply the model to a study of secondary breast cancer events, utilizing mammography and biopsy records from a sample of women with a history of primary breast cancer.

Preoperative consultations for medicare patients undergoing cataract surgery

IMPORTANCE

Low-risk elective surgical procedures are common, but there are no clear guidelines for when preoperative consultations are required. Such consultations may therefore represent a substantial discretionary service.

OBJECTIVE

To assess temporal trends, explanatory factors, and geographic variation for preoperative consultation in Medicare beneficiaries undergoing cataract surgery, a common low-risk elective procedure.

DESIGN, SETTING, AND PARTICIPANTS

Cohort study using a 5% national random sample of Medicare part B claims data including a cohort of 556,637 patients 66 years or older who underwent cataract surgery from 1995 to 2006. Temporal trends in consultations were evaluated within this entire cohort, whereas explanatory factors and geographic variation were evaluated within the 89,817 individuals who underwent surgery from 2005 to 2006.

MAIN OUTCOMES AND MEASURES

Separately billed preoperative consultations (performed by family practitioners, general internists, pulmonologists, endocrinologists, cardiologists, nurse practitioners, or anesthesiologists) within 42 days before index surgery.

RESULTS

The frequency of preoperative consultations increased from 11.3% in 1998 to 18.4% in 2006. Among individuals who underwent surgery in 2005 to 2006, hierarchical logistic regression modeling found several factors to be associated with preoperative consultation, including increased age (75-84 years vs 66-74 years: adjusted odds ratio [AOR], 1.09 [95% CI, 1.04-1.13]), race (African American race vs other: AOR, 0.71 [95% CI, 0.65-0.78]), urban residence (urban residence vs isolated rural town: AOR, 1.64 [95% CI, 1.49-1.81]), facility type (outpatient hospital vs ambulatory surgical facility: AOR, 1.10 [95% CI, 1.05-1.15]), anesthesia provider (anesthesiologist vs non-medically directed nurse anesthetist: AOR, 1.16 [95% CI, 1.10-1.24), and geographic region (Northeast vs South: AOR, 3.09 [95% CI, 2.33-4.10]). The burden of comorbidity was associated with consultation, but the effect size was small (<10%). Variation in frequency of consultation across hospital referral regions was substantial (median [range], 12% [0-69%]), even after accounting for differences in patient-level, anesthesia provider-level, and facility-level characteristics.

CONCLUSIONS AND RELEVANCE

Between 1995 and 2006, the frequency of preoperative consultation for cataract surgery increased substantially. Referrals for consultation seem to be primarily driven by nonmedical factors, with substantial geographic variation.

Outcomes and utilization of a low intensity workplace weight loss program

Obesity is related to high health care costs and lost productivity in the workplace. Employers are increasingly sponsoring weight loss and wellness programs to ameliorate these costs. We evaluated weight loss outcomes, treatment utilization, and health behavior change in a low intensity phone- and web-based, employer-sponsored weight loss program. The intervention included three proactive counseling phone calls with a registered dietician and a behavioral health coach as well as a comprehensive website. At six months, one third of those who responded to the follow-up survey had lost a clinically significant amount of weight (≥5% of body weight). Clinically significant weight loss was predicted by the use of both the counseling calls and the website. When examining specific features of the web site, the weight tracking tool was the most predictive of weight loss. Health behavior changes such as eating more fruits and vegetables, increasing physical activity, and reducing stress were all predictive of clinically significant weight loss. Although limited by the low follow-up rate, this evaluation suggests that even low intensity weight loss programs can lead to clinical weight loss for a significant number of participants.

Pulmonary disease after treatment for Wilms tumor: a report from the national wilms tumor long-term follow-up study

PURPOSE

This study was undertaken to evaluate the incidence of pulmonary disease among patients treated with radiation therapy (RT) for pulmonary metastases (PM) from Wilms tumor (WT).

PATIENTS AND METHODS

We reviewed records of 6,449 patients treated on National Wilms Tumor Studies-1, -2, -3, and -4 whose flow sheets or annual status reports documented one of several pulmonary conditions. Cases were fully evaluable if pulmonary function test (PFT) results were available, pulmonary fibrosis was identified on a chest radiograph or was listed as the primary or a contributing factor to death. Partially evaluable cases were those for whom PFT results could not be obtained. We evaluated the relationship between RT factors and the occurrence of pulmonary disease using hazard ratios (HRs) and cumulative incidence, treating death as a competing risk.

RESULTS

Sixty-four fully evaluable and 16 partially evaluable cases of pulmonary disease were identified. The cumulative incidence of pulmonary disease at 15 years since WT diagnosis was 4.0% (95% confidence interval [CI] 2.6-5.4%) among fully evaluable and 4.8% (95% CI 3.3-6.4%) among fully and partially evaluable patients who received lung RT for PM at initial diagnosis. Rates of pulmonary disease were substantially higher among those who received lung RT for PM present at initial diagnosis or relapse compared to those who received no RT or only abdominal RT (HR 30.2, 95% CI 16.9-53.9).

CONCLUSION

The risk of pulmonary disease must be considered in evaluating the risk:benefit ratio of lung RT for the management of PM from WT.

Fitting and interpreting continuous-time latent Markov models for panel data

Multistate models characterize disease processes within an individual. Clinical studies often observe the disease status of individuals at discrete time points, making exact times of transitions between disease states unknown. Such panel data pose considerable modeling challenges. Assuming the disease process progresses accordingly, a standard continuous-time Markov chain (CTMC) yields tractable likelihoods, but the assumption of exponential sojourn time distributions is typically unrealistic. More flexible semi-Markov models permit generic sojourn distributions yet yield intractable likelihoods for panel data in the presence of reversible transitions. One attractive alternative is to assume that the disease process is characterized by an underlying latent CTMC, with multiple latent states mapping to each disease state. These models retain analytic tractability due to the CTMC framework but allow for flexible, duration-dependent disease state sojourn distributions. We have developed a robust and efficient expectation-maximization algorithm in this context. Our complete data state space consists of the observed data and the underlying latent trajectory, yielding computationally efficient expectation and maximization steps. Our algorithm outperforms alternative methods measured in terms of time to convergence and robustness. We also examine the frequentist performance of latent CTMC point and interval estimates of disease process functionals based on simulated data. The performance of estimates depends on time, functional, and data-generating scenario. Finally, we illustrate the interpretive power of latent CTMC models for describing disease processes on a dataset of lung transplant patients. We hope our work will encourage wider use of these models in the biomedical setting.

Secondary malignant neoplasms after Wilms tumor: an international collaborative study

A combined cohort of 8,884 North American, 2,893 British and 1,574 Nordic subjects with Wilms tumor (WT) diagnosed before 15 years of age during 1960-2004 was established to determine the risk of secondary malignant neoplasms (SMN). After 169,641 person-years (PY) of observation through 2005, 174 solid tumors (exclusive of basal cell carcinomas) and 28 leukemias were ascertained in 195 subjects. Median survival time after a solid SMN diagnosis 5 years or more from WT was 11 years; it was 10 months for all leukemia. Age-specific incidence of secondary solid tumors increased from approximately 1 case per 1,000 PY at age 15 to 5 cases per 1,000 PY at age 40. The cumulative incidence of solid tumors at age 40 for subjects who survived free of SMNs to age 15 was 6.7%. Leukemia risk, by contrast, was highest during the first 5 years after WT diagnosis. Standardized incidence ratios (SIRs) for solid tumors and leukemias were 5.1 and 5.0, respectively. Results for solid tumors for the 3 geographic areas were remarkably consistent; statistical tests for differences in incidence rates and SIRs were all negative. Age-specific incidence rates and SIRs for solid tumors were lower for patients whose WT was diagnosed after 1980, although the trends with decade of diagnosis were not statistically significant. Incidence rates and SIRs for leukemia were highest among those diagnosed after 1990 (p-trend = 0.003). These trends may reflect the decreasing use of radiation therapy and increasing intensity of chemotherapy in modern protocols for treatment of WT.

Pregnancy outcome after treatment for Wilms tumor: a report from the national Wilms tumor long-term follow-up study

PURPOSE

This study was undertaken to evaluate the effect of prior treatment with radiation therapy or chemotherapy for unilateral Wilms tumor (WT) diagnosed during childhood on pregnancy complications, birth weight, and the frequency of congenital malformations in live-born offspring.

PATIENTS AND METHODS

We reviewed pregnancy outcomes among female survivors and partners of male survivors of WT treated on National Wilms Tumor Studies 1, 2, 3, and 4 by using a maternal questionnaire and a review of both maternal and offspring medical records.

RESULTS

We received reports of 1,021 pregnancies with duration of 20 weeks or longer, including 955 live-born singletons, for whom 700 sets of maternal and offspring medical records were reviewed. Rates of hypertension complicating pregnancy (International Classification of Diseases [ICD] code 642), early or threatened labor (ICD-644) and malposition of the fetus (ICD-652) increased with increasing radiation dose in female patients. The percentages of offspring weighing less than 2,500 g at birth and of those having less than 37 weeks of gestation also increased with dose. There was no significant trend with radiation dose in the number of congenital anomalies recorded in offspring of female patients.

CONCLUSION

Women who receive flank radiation therapy as part of the treatment for unilateral WT are at increased risk of hypertension complicating pregnancy, fetal malposition, and premature labor. The offspring of these women are at risk for low birth weight and premature (ie, < 37 weeks gestation) birth. These risks must be considered in the obstetrical management of female survivors of WT.

Perceived need for care among low-income immigrant and U.S.-born black and Latina women with depression

PURPOSE

To examine perceived need for care for mental health problems as a possible contributor to ethnic disparities in receiving care among low-income depressed women.

METHODS

The role of ethnicity, somatization, and stigma as they relate to perceived need for care is examined. Participants were 1577 low-income women who met criteria for depression.

RESULTS

Compared with U.S.-born depressed white women, most depressed ethnic minority women were less likely to perceive a need for mental health care (black immigrants: OR 0.30, p < 0.001; U.S.-born blacks: OR 0.43, p < 0.001; immigrant Latinas: OR 0.52, p < 0.01). Stigma-related concerns decreased the likelihood of perceiving a need for mental health care (OR 0.80, p < 0.05). Having multiple somatic symptoms (OR 1.57, p < 0.001) increased the likelihood of endorsing perceived need.

CONCLUSIONS

Findings suggest that there are ethnic differences in perceived need for mental healthcare that may partially account for the low rates of care for depression among low-income and minority women. The relations among stigma, somatization, and perceived need were strikingly similar across ethnic groups.

Mental health care preferences among low-income and minority women

Mental health care preferences are examined among 1,893 low-income immigrant and U.S.-born women with an acknowledged emotional problem (mean age = 29.1, SD = 89.6). Ethnicity, depression, somatization, and stigma are examined as they relate to mental health care preferences (medication, individual and group counseling, faith, family/friends). Seventy-eight percent of participants counseling would be helpful; 55%; group counseling; and 32% medication. Faith was cited by 81%; family and friends were endorsed by 65%. Minorities had lower odds than Whites of endorsing medication (Black immigrants: OR = 0.27, p < 0.001, U.S.-born Blacks: OR = 0.30, p < 0.001, immigrant Latinas: OR = 0.50, p < 0.01). Most minorities also had higher odds of endorsing faith compared to Whites (Black immigrants: OR = 3.62, p < 0.001; U.S.-born Blacks, OR = 3.85, p < 0.001; immigrant Latinas: OR = 9.76, p < 0.001). Being depressed was positively associated with endorsing medication (OR = 1.93, p < 0.001), individual counseling (OR = 2.66, p < 0.001), and group counseling (OR = 1.35, p < 0.01). Somatization was positively associated with endorsing medication (OR = 1.29, p < 0.05) and faith (OR = 1.37, p < 0.05). Stigma-concerns reduced the odds of endorsing group counseling (OR = 0.58, p < 0.001). Finally, being in mental health treatment was related to increased odds of endorsing medication (OR = 3.88, p < 0.001) and individual counseling (OR = 2.29, p = 0.001).

Does stigma keep poor young immigrant and U.S.-born Black and Latina women from seeking mental health care?

OBJECTIVE

This study examined the extent to which stigma-related concerns about mental health care account for the underuse of mental health services among low-income immigrant and U.S.-born black and Latina women.

METHODS

Participants included 15,383 low-income women screened for depression in county entitlement services who were asked about barriers to care, stigma-related concerns, and whether they wanted or were getting mental health care.

RESULTS

Among those who were depressed, compared with U.S.-born white women, each of the black groups were more likely to report stigma concerns (African immigrants, odds ratio [OR]=3.28, p=.004; Caribbean immigrants, OR=6.17, p=.005; U.S.-born blacks, OR=6.17, p=.06). Compared with U.S.-born white women, immigrant African women (OR=.18, p<.001), immigrant Caribbean women (OR=.11, p=.001), U.S.-born black women (OR=.31, p<.001), and U.S.-born Latinas (OR=.32, p=.03) were less likely to want treatment. Conversely, compared with U.S.-born white women, immigrant Latinas (OR=2.17, p=.02) were more likely to want treatment. There was a significant stigma-by-immigrant interaction predicting interest in treatment (p<.001). Stigma reduced the desire for mental health treatment for immigrant women with depression (OR=.35, p<.001) to a greater extent than it did for U.S.-born white women with depression (OR=.52, p=.24).

CONCLUSIONS

Stigma-related concerns are most common among immigrant women and may partly account for underutilization of mental health care services by disadvantaged women from ethnic minority groups.

[The use of the non-nucleoside reverse transcriptase inhibitors nevirapine and efavirenz in the treatment of patients with a chronic HIV-I infection]

The non-nucleoside reverse transcriptase inhibitors (NNRTIs) are an important group ofantiretroviral drugs in the treatment of a chronic HIV-I infection. The risk of viral resistance to NNRTIs is strongly diminished when they are used as part of a highly active antiretroviral combination therapy (HAART). Randomised trials have shown that nevirapine and efavirenz have a comparable antiretroviral efficacy. While rash and hepatotoxicity are associated with the use of nevirapine, the use of efavirenz is associated with neuropsychiatric abnormalities. The increase in HDL-cholesterol, which may be associated with a lower risk of cardiovascular disease, is greater with nevirapine than with efavirenz. The choice between the two drugs can be tailored to the needs of the patient. The rapid selection ofNNRTI-resistant HIV-I strains during the sub-optimal use of nevirapine and efavirenz demands the development of new NNRTIs.

Adequacy of peritoneal dialysis and the importance of preserving residual renal function

The well-being and survival of dialysis patients not only depend on the removal of waste products and excess fluid, but also on the prevention of cardiovascular complications by maintaining normovolaemia and adequate blood pressure and avoidance of ectopic calcification. Also, the maintenance of nutritional status and adequate removal of middle molecules are amongst the most important issues in long-term renal replacement therapy. In this review, attention is given to optimal peritoneal small solute clearance and Kt/V and to the evidence concerning the role of residual renal function. In addition, factors that can influence this residual function are also discussed.

[Coinfection with hepatitis C virus and HIV]

The life expectancy of patients with an HIV infection has improved dramatically since the introduction of highly active anti-retroviral therapy (HAART). Retrospective studies have shown that since then, hospital admissions and mortality caused by a co-infection with hepatitis C virus (HCV) have increased. Patients with an HIV-HCV co-infection exhibit on average a more rapid progression to liver cirrhosis and liver failure than patients with an HCV monoinfection. It is expected that a co-infection with HCV will lead to serious complications among some of the HIV-infected population. It is therefore recommended that all HIV-infected patients be screened for a co-infection with HCV. The treatment of an HCV co-infection needs to be considered. The first choice therapy will probably be a combination of peginterferon and ribavirin, although final conclusions about the safety and efficacy are still awaited. A combination of ribavirin with zidovudine or didanosine is best avoided. Developments being made with new classes of drugs, such as HCV-specific protease inhibitors and polymerase inhibitors, seem promising.

Triple Nucleoside Combination Zidovudine/Lamivudine/Abacavir versus Zidovudine/Lamivudine/Nelfinavir as First-Line Therapy in HIV-1-Infected Adults: A Randomized Trial

Objective

To compare the efficacy and safety of a triple nucleoside combination to a protease inhibitor-containing triple regimen as first-line antiretroviral therapy (ART) in HIV-1-infected patients.

Design

Open-label study in HIV-1-infected ART-naive adults, randomized to receive either Combivir® (lamivudine 150 mg/zidovudine 300 mg twice daily) + abacavir (300 mg twice daily), or Combivir® + nelfinavir (750 mg every 8 h) for 48 weeks. Plasma HIV-1 RNA, CD4 cell count and adverse events were assessed at baseline and weeks 4, 8, 16, 24, 32, 40 and 48.

Results

195 subjects (131 men, 64 women), median age 34 years, were randomized: 98 received combivir/abacavir and 97 combivir/nelfinavir. Baseline median plasma HIV-1 RNA was 4.2 log10 copies/ml [Interquartile range (IQR): 3.7-4.5.2] and 4.1 log10 copies/ml (IQR: 3.8–4.6), respectively. Baseline median CD4 cell count was 387 cells/mm3 (IQR: 194–501) and 449 cells/mm3 (IQR: 334–605), respectively. Nine patients (3 vs 6, respectively) did not start treatment or did not have any available efficacy data. At week 48, using the intent to treat analysis (switch/missing equals failure), plasma HIV-1 RNA was <50 copies/ml in 54/95 (57%) and 53/91 (58%) of subjects, respectively. Median CD4 increase was +110 and +120 cells/mm3, respectively. Possible hypersensitivity reactions to abacavir were reported in four subjects (4%).

Conclusion

The triple nucleoside combination combivir/abacavir is well tolerated as a first-line ART regimen in HIV-1-infected adults, with comparable antiviral activity to a nelfinavir-containing regimen at week 48.

Prednisolone does not prevent hypersensitivity reactions in antiretroviral drug regimens containing abacavir with or without nevirapine

OBJECTIVES

To determine the effect of adjuvant prednisolone use on the development of abacavir (ABC)- and nevirapine (NVP)-associated hypersensitivity reactions (HSR).

METHODS

Randomized open-label study in antiretroviral-naive adult HIV-1 infected patients using a factorial design in which NVP and/or hydroxyurea (HU) and/or prednisolone are added to a regimen of ABC, zidovudine and lamivudine. Prednisolone (40 mg once daily) was added for the first 2 weeks of treatment. As it was difficult to distinguish ABC-associated HSR from NVP-associated HSR, these events were treated as a composite endpoint. The odds ratio (OR) of developing HSR for prednisolone-use was calculated with and without stratification by NVP and/or HU. Logistic regression was performed to identify risk factors for developing HSR.

RESULTS

Of the 229 patients 115 were randomized to prednisolone and 114 to no-prednisolone; 19 (17%) and 11 (10%) patients, respectively, developed HSR. The expected prevention of HSR by prednisolone use was not observed. In fact use of prednisolone showed an increased risk for HSR although this did not reach statistical significance [OR, 1.82; 95% confidence interval (CI), 0.82-4.03]. There was a higher incidence of HSR in the NVP group than in the non-NVP group (20% versus 6%; P = 0.002). An additional risk factor identified in a multivariate logistic model was a high baseline CD4 cell count (OR, 1.26 per 100 x 10(6) cells/l increase; 95% CI, 1.06-1.51).

CONCLUSIONS

The simultaneous start of ABC and NVP in first-line antiretroviral regimens should be avoided because of a high (20%) incidence of HSR. Short-term therapy with prednisolone did not prevent HSR in patients using ABC with or without NVP.

Combination of protease inhibitors for the treatment of HIV-1-infected patients: a review of pharmacokinetics and clinical experience

The use of highly active antiretroviral therapy, the combination of at least three different antiretroviral drugs for the treatment of HIV-1 infection, has greatly improved the prognosis for HIV-1-infected patients. The efficacy of a combination of a protease inhibitor (PI) plus two nucleoside analogue reverse transcriptase inhibitors has been well established over a period of up to 3 years. However, virological treatment failure has been reported in 40-60% of unselected patients within 1 year after initiation of a PI-containing regimen. This observation may, at least in part, be attributed to the poor pharmacokinetic characteristics of the PIs. Given as a single agent the PIs have several pharmacokinetic limitations; relatively short plasma-elimination half-lives and a modest and variable oral bioavailability, which is, for some of the PIs, influenced by food. To overcome these suboptimal pharmacokinetics, high doses (requiring large numbers of pills) must be ingested, often with food restrictions, which complicates patient adherence to the prescribed regimen. Positive drug-drug interactions increase the exposure to the PIs, allowing administration of lower doses at reduced dosing frequencies with less dietary restrictions. In addition to increasing the potency of an antiretroviral regimen, combinations of PIs may enhance patient adherence, both of which will contribute to a more durable suppression of viral replication. The favourable pharmacokinetics of PIs in combination are a result of interactions through cytochrome P450 3A4 (CYP3A4) isoenzymes and, possibly, the multi-drug transporting P-glycoprotein (P-gp). Antiretroviral synergy between PIs and non-overlapping primary resistance patterns in the HIV-1 protease genome may further enhance the antiretroviral potency and durability of combinations of PIs. Many combinations contain ritonavir because this PI has the most pronounced inhibiting effects on CYP3A4. The combination of saquinavir and ritonavir, both in a dose of 400 mg twice-a-day, is the most studied double PI combination, with clinical experience extending over 3 years. Combination of a PI with a low dose of ritonavir (< or = 400 mg/day), only to boost its pharmacokinetic properties, seems an attractive option for patients who cannot tolerate higher doses of ritonavir. A recently introduced PI, lopinavir, has been co-formulated with low-dose ritonavir, which allows for a convenient three-capsules, twice-a-day dosing regimen. In an attempt to prolong suppression of viral replication combinations of PIs are becoming increasingly popular. However, further clinical studies are needed to identify the optimal combinations for treatment of antiretroviral naive and experienced HIV-1-infected patients. This review covers combinations of saquinavir, indinavir, nelfinavir, amprenavir and lopinavir with different doses of ritonavir, as well as the combinations of saquinavir and indinavir with nelfinavir.

Limited sampling strategies for the estimation of the systemic exposure to the HIV-1 nonnucleoside reverse transcriptase inhibitor nevirapine

The objective of this study was to develop and validate a limited sampling strategy (LSS) that allows accurate and precise estimation of the area under the plasma concentration versus time curve (AUC) of nevirapine, when used in the licensed dosage of 200 mg twice daily. Because nevirapine has a long plasma elimination half-life and the plasma concentration shows little variation within the 12-hour dosing interval, the authors also wanted to explore whether a time frame exists for which a single-sample LSS can be applied. Twenty HIV-1-infected individuals receiving steady-state treatment with nevirapine (200 mg twice daily) were enrolled. For the development of the LSS, 10 patients were randomly selected from the study population (index set). The pharmacokinetic results from the other 10 patients (validation set) were used for prospective validation of the proposed LSS. Blood samples were obtained before and 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 10, and 12 hours after ingestion. The relationship between the nevirapine concentration at each of the designated time points and the AUC 12h was evaluated by univariate and multivariate linear regression analysis. At each of the sampling times, a strong correlation was observed between the nevirapine concentration and the corresponding AUC 12h (r > 0.97). This allows for a single-sample LSS, using any time point during the dosing interval. When a single equation is preferred, the concentration of nevirapine in a random sample drawn 2 to 4 hours after ingestion of nevirapine (C 2-4h; in microg/mL) can be used for accurate estimation of the AUC 12h (in h x microg/mL) by using the equation AUC 12h (h x microg/mL) = 11.699 (h) x C 2-4h (microg/mL) - 4.381 (h x microg/mL). Validation of this equation resulted in a predicted AUC 12h that was nonbiased and very precise. These data show that the nevirapine concentration at each time point during the dosing interval can be used for accurate estimation of the AUC 12h. Even more practical, a sample obtained at any time between 2 and 4 hours after ingestion of nevirapine can be used. The authors therefore conclude that less intensive sampling (i.e., a single sample) can readily be used to assess the AUC 12h of nevirapine when used in a dosage of 200 mg twice daily.

Pharmacokinetics of stavudine and didanosine coadministered with nelfinavir in human immunodeficiency virus-exposed neonates

We evaluated the pharmacokinetics of stavudine (d4T) and didanosine (ddI) in neonates. Eight neonates born to human immunodeficiency virus-infected mothers were enrolled to receive 1 mg of d4T per kg of body weight twice daily and 100 mg of ddI per m(2) once daily in combination with nelfinavir for 4 weeks after birth. Pharmacokinetic evaluations were performed at 14 and 28 days of age. For d4T, on days 14 and 28, the median areas under the concentration-time curves from 0 to 12 h (AUC(0-12)s) were 1,866 and 1,603, ng x h/ml, respectively, and the median peak concentrations (C(max)s) were 463 and 507 ng/ml, respectively. For ddI, on days 14 and 28, the median AUC(0-10)s were 1,573 and 1,562 h x ng/ml, respectively, and the median C(max)s were 627 and 687 ng/ml, respectively. Systemic levels of exposure to d4T were comparable to those seen in children, suggesting that the pediatric dose of 1 mg/kg twice daily is appropriate for neonates at 2 to 4 weeks of age. Levels of exposure to ddI were modestly higher than those seen in children. Whether this observation warrants a reduction of the ddI dose in neonates is unclear.

Carrier rate of zidovudine-resistant HIV-1: the impact of failing therapy on transmission of resistant strains

OBJECTIVE

Because maintenance of treatment success in HIV-1 infection requires viruses to remain therapy sensitive in drug-naive seropositive persons, we looked at the primary infections caused by drug-resistant HIV-1 over time. Furthermore, to study the coverage rate of therapy and therapy failure in relation to the transmission of resistant viruses a mathematical model was developed.

DESIGN

The reverse transcriptase and protease genes of viruses were analysed in newly infected people in the period 1990-1998 in the Amsterdam Cohort Study on HIV infection and AIDS in homosexual men.

METHODS

The mathematical model was based on the coverage of drug regimens selecting zidovudine (ZDV) resistance, the lag time in which resistance is gained or lost, the death rate of people infected with resistant virus, and the replacement of resistance-selecting regimens by more potent treatments that substantially reduce viral load and mortality.

RESULTS

Of 43 individuals with a primary HIV-infection, three (7%) harboured ZDV-resistant viruses. The first of the ZDV-resistant strains was transmitted in 1995, the last two in 1996. The build-up of ZDV resistance was described by the mathematical model indicating that the equilibrium level of resistance due to treatment depends only on the treatment rate and the outflow rate of patients with resistance virus.

CONCLUSIONS

Our model indicates that the frequency of viral resistance in a population is determined largely by the number of individuals on insufficient or failing therapy and is influenced only modestly by secondary transmission of ZDV-resistant strains.

Therapeutic immune reconstitution in HIV-1-infected children is independent of their age and pretreatment immune status

OBJECTIVE

To evaluate long-term immune reconstitution of children treated with highly active antiretroviral therapy (HAART).

METHODS

The long-term immunological response to HAART was studied in 71 HIV-1-infected children (aged 1 month to 18 years) in two prospective, open, uncontrolled national multicentre studies. Blood samples were taken before and after HAART was initiated, with a follow-up of 96 weeks, and peripheral CD4 and CD8 T cells plus naive and memory subsets were identified in whole blood samples. Relative cell counts were calculated in relation to the median of the age-specific reference.

RESULTS

The absolute CD4 cell count and percentage and the CD4 cell count as a percentage of normal increased significantly (P < 0.001) to medians of 939 x 106 cells/l (range, 10-3520), 32% (range, 1-50) and 84% (range, 1-161), respectively, after 48 weeks. This increase was predominantly owing to naive CD4 T cells. There was a correlation between the increase of absolute naive CD4 T cell counts and age. However, when CD4 T cell restoration was studied as percentage of normal values, the inverse correlation between the increase of naive CD4 T cell count and age was not observed. In addition, no difference in immunological reconstitution was observed at any time point between virological responders and non-responders.

CONCLUSIONS

Normalization of the CD4 cell counts in children treated with HAART is independent of age, indicating that children of all age groups can meet their CD4 T cell production demands. In general, it appears that children restore their CD4 T cell counts better and more rapidly than adults, even in a late stage of HIV-1 infection.

Lipodystrophy in HIV-1-positive patients is associated with insulin resistance in multiple metabolic pathways

BACKGROUND

Treatment for HIV-1 infection is complicated by fat redistribution (lipodystrophy). This is associated with insulin resistance concerning glucose uptake. Our aim was to characterize glucose metabolism more comprehensively in HIV-1-infected patients with lipodystrophy. We assessed glucose disposal and its pathways, glucose production, plasma free fatty acid (FFA) levels, and the degree to which these parameters could be suppressed by insulin.

METHODS

Six HIV-1-infected men on protease inhibitor-based HAART with lipodystrophy (HIV+LD) were studied. The results were compared with those in six matched healthy male volunteers. Insulin sensitivity was quantified by hyperinsulinemic euglycaemic clamp. Glucose production and uptake were assessed by tracer dilution employing 6,6D(2)-glucose.

RESULTS

At post-absorptive insulin concentrations, glucose production was 47% higher in HIV+LD than controls (P = 0.025). During clamp, glucose production was suppressed by 53% in HIV+LD, but by 85% in controls (P = 0.004). Glucose disposal increased in both groups, but by only 27% in HIV+LD versus 201% in controls (P = 0.004). Consequently, insulin-stimulated total glucose disposal was lower in HIV+LD patients (P = 0.006). Non-oxidative glucose disposal as percentage of total disposal did not differ significantly between groups (63% in HIV+LD and 62% in controls). Baseline plasma FFA concentrations were higher (0.60 versus 0.35 mmol/l; P = 0.024), whereas FFA decline during hyperinsulinemia was less (65 versus 85%; P = 0.01) in HIV+LD versus controls.

CONCLUSIONS

Post-absorptive glucose production is increased in HIV-1-infected patients with lipodystrophy. Moreover, both the ability of insulin to suppress endogenous glucose production and lipolysis, and to stimulate peripheral glucose uptake and its metabolic pathways is reduced, indicating severe resistance concerning multiple effects of insulin.

Long-term quality of life outcomes in three antiretroviral treatment strategies for HIV-1 infection

OBJECTIVE

To compare changes in quality of life (QoL) over 96 weeks in patients enrolled in a triple-therapy protocol, a treatment-intensification protocol, or an induction-maintenance therapy protocol, and to compare QoL between patients who continued and discontinued their antiretroviral regimen.

PATIENTS

Naive patients enrolled in a triple-therapy protocol (zidovudine/lamivudine or stavudine/didanosine or stavudine/lamivudine supplemented with protease inhibitor therapy of choice) (n = 35), a protocol of treatment intensification (ritonavir/saquinavir or ritonavir/saquinavir/stavudine) (n = 74) in which therapy was intensified with nucleoside analogue(s) in cases of insufficient viral suppression, and a protocol of induction (saquinavir/nelfinavir/lamivudine/ stavudine) maintenance (saquinavir/nelfinavir or stavudine/nelfinavir) therapy (n = 50).

MAIN OUTCOME MEASURE

Changes from baseline in QoL assessed by the Medical Outcomes Study HIV Health Survey at weeks 0, 12, 24, 36, 48, 72 and 96.

RESULTS

Patients in the triple-therapy and treatment-intensification protocols showed more favourable changes in physical function, social function, mental health, energy/fatigue, health distress and overall QoL compared to patients in the induction-maintenance protocol, with patients in the first two protocols showing improvements in QoL and those in the induction-maintenance protocol showing declining or unchanged QoL. Patients who discontinued study medication due to insufficient efficacy, toxicities or at their own request showed less favourable changes in QoL compared with patients who continued their regimen. The highest proportion of discontinuations was within the induction-maintenance protocol.

CONCLUSION

Antiretroviral treatment strategies that are effective and tolerable have the potential to improve patients' QoL over 96 weeks.

Penetration of the nucleoside analogue abacavir into the genital tract of men infected with human immunodeficiency virus type 1

The male genital tract is considered an anatomical reservoir during therapy for human immunodeficiency virus infection, because the blood-testis barrier may prevent antiretroviral drugs (e.g., the protease inhibitors ritonavir, saquinavir and nelfinavir) from entering the male genital tract. To our knowledge, there are currently no available data on the penetration of the nucleoside analogue abacavir into the male genital tract. Our report shows that abacavir has good penetration into the male genital tract.

Pharmacokinetic profiles of nevirapine and indinavir in various fractions of seminal plasma

Limited data are available on antiretroviral drug concentrations in seminal plasma during a dosing interval. Further, since human ejaculate is composed of fluids originating from the testes, the seminal vesicles, and the prostate, all having different physiological characteristics, drug concentrations in total seminal plasma do not necessarily reflect concentrations in the separate compartments. Five human immunodeficiency virus type 1-infected patients on nevirapine (NVP; 200 mg twice a day [b.i.d.]) and/or indinavir (IDV; 800 mg b.i.d. with ritonavir, 100 mg b.i.d.) regimens used a split ejaculate technique to separate seminal plasma in two fractions, representing fluids from the testes and prostate (first fraction) and fluids from the seminal vesicles (second fraction). Split-ejaculate samples were provided at 0, 2, 5, and 8 h after drug ingestion, on separate days after 3 days of sexual abstinence. NVP and IDV showed time-dependent concentrations in seminal plasma, with peak concentrations in both fractions at 2 and 2 to 5 h, respectively, after drug ingestion. The NVP concentrations were not significantly different between the first and second fractions of the ejaculate at all time points measured and were in the therapeutic range, except for the predose concentration in two patients. The median (range) predose IDV concentrations in the first and second fractions of the ejaculate were 448 (353 to 1,015) ng/ml and 527 (240 to 849) ng/ml, respectively (P = 0.7). In conclusion, NVP and IDV concentrations in seminal plasma are dependent on the time after drug ingestion. Furthermore, our data suggest that NVP and IDV achieve therapeutic concentrations in both the testes and prostate and the seminal vesicles throughout the dosing interval.

Limited patient adherence to highly active antiretroviral therapy for HIV-1 infection in an observational cohort study

BACKGROUND

Adherence to highly active antiretroviral therapy (HAART) for human immunodeficiency syndrome type 1 (HIV-1) infection is essential to sustain viral suppression and prevent drug resistance. We investigated adherence to HAART among patients in a clinical cohort study.

METHODS

Patients receiving HAART had their plasma concentrations of protease inhibitors or nevirapine measured and completed a questionnaire on adherence. We determined the percentage of patients who reported taking all antiretroviral medication on time and according to dietary instructions in the past week. Drug exposure was compared between patients reporting deviation from their regimen and fully adherent patients. Among patients who received HAART for at least 24 weeks, we assessed the association between adherence and virologic outcome.

RESULTS

A total of 224 of 261 eligible patients completed a questionnaire. Forty-seven percent reported taking all antiretroviral medication on time and according to dietary instructions. Patients who reported deviation from their regimen showed lower drug exposure compared with fully adherent patients (median concentration ratio, 0.81 vs 1.07; P =.001). Among those receiving HAART for at least 24 weeks, patients reporting deviation from their regimen were less likely to have plasma HIV-1 RNA levels below 500 copies/mL (adjusted odds ratio, 4.0; 95% confidence interval, 1.4-11.6) compared with fully adherent patients.

CONCLUSIONS

Only half of the patients took all antiretroviral medication in accordance with time and dietary instructions in the preceding week. Deviation from the antiretroviral regimen was associated with decreased drug exposure and a decreased likelihood of having suppressed plasma HIV-1 RNA loads. Patient adherence should remain a prime concern in the management of HIV-1 infection.

[HIV-1 therapy in the Netherlands; virological and immunological response to antiretroviral therapy]

OBJECTIVE

To evaluate the effect of treatment of HIV-1 infection with combination therapy consisting of since 1996 in the Netherlands available protease and reverse transcriptase inhibitors.

DESIGN

Prospective cohort study.

METHODS

In an observational clinical cohort of HIV-1-infected individuals, the short-term successful treatment end point of antiviral therapy including at least one antiretroviral drug licensed in the Netherlands since July 1, 1996 (protease inhibitors and reverse transcriptase inhibitors), was HIV-1 RNA plasma levels < or = 500 copies/ml (virological success). Cox proportional hazard models were used to identify prognostic markers for therapy success. The study included 2,148 infected individuals with a median follow-up of 135 weeks of treatment; 1,049 had been pre-treated with antiretroviral drugs before starting their new regimen and 1,099 were treatment naive.

RESULTS

Plasma HIV-1 RNA levels < or = 500 copies/ml at 24 weeks of treatment were seen in 61% of all patients. The chance of therapy success for naive patients was twice that for pre-treated patients (relative risk: 1.8; p < or = 0.001). Following the first 24 weeks, the chance of virological success was higher in the naive group (78% versus 63%; p < or = 0.001), and the number of naive patients failing therapy after initial success was smaller compared to pre-treated patients (22% versus 45%; p < or = 0.001). In the naive group, the CD4+ T-cell number increased from 239 to 440 (x 10(6) cells/l) in case of success, and decreased from 150 to 320 in case of treatment failure. HIV-1 related morbidity declined from 0.26 to 0.05 and mortality dropped from 0.07 to 0.03 per person-year of follow-up. Regimens were changed at least once in 76% of patients. Toxicity and therapy failure were the main reasons for regimen changes in naive and pre-treated patients, respectively.

CONCLUSION

A combination of antiretroviral drugs, including at least one of the drugs licensed since 1996, led to a drop in HIV-1 plasma concentrations. Morbidity and mortality also decreased. The chance of a better immunological and virological response to the new drug regimens was greatest in therapy-naive patients.

[CBO guidelines 'Antiretroviral therapy in the Netherlands']

In collaboration with the Dutch Institute for Health Care Improvement (CBO) and on the basis of recent developments, new guidelines have been developed for the diagnosis and treatment of HIV-infected patients. The most important recommendations are: Treatment of adult patients is indicated if HIV load > 30,000 RNA copies/ml, or when CD4+ cell count is < 350 x 10(6) cells/l. Treatment of children is indicated if HIV load > 5,000 copies/ml, even when CD4+ cell count is > 500 x 10(6) cells/l. Optimal antiretroviral treatment consists of a combination of two nucleoside reverse transcriptase inhibitors (NRTIs) and one protease inhibitor, or a combination of two NRTIs and one non-nucleoside reverse transcriptase inhibitor. Patients on antiretroviral treatment should be monitored every 3 months. Undetectable HIV load should be the target of first- or second-line antiretroviral treatment. In order to prevent HIV transmission from mother to child, prescription of antiretroviral drugs after the first three months of pregnancy is indicated in pregnant women with a detectable HIV load. Prophylaxis of opportunistic infections can be discontinued if CD4+ cell count recovers above 200 x 10(6)/l. In case of exposure to HIV due to a needle or other occupational accident or unsafe sexual contact, post-exposure prophylaxis should be offered after careful risk evaluation. Preferably, vaccination to prevent pneumococci infections, influenza, hepatitis A or hepatitis B should be given when CD4+ cell count is > 200 x 10(6)/l.

Steady-state pharmacokinetics of twice-daily dosing of saquinavir plus ritonavir in HIV-1-infected individuals

OBJECTIVE

To compare the steady state plasma pharmacokinetics of 1000 mg of saquinavir (SQV) in a soft-gel capsule (SGC) formulation in combination with 100 mg of ritonavir (RTV) (capsules) in a twice-daily dosing regimen in HIV-1-infected individuals with historical controls who used 400 mg of SQV in a hard-gel capsule (HGC) formulation in combination with 400 mg of RTV and to investigate the plasma pharmacokinetics of the 1000 mg/100 mg regimen after normal and high-fat breakfasts.

DESIGN

Open-label, crossover, steady-state pharmacokinetic study.

METHODS

Six HIV-1-infected individuals who used either 1200 mg of SQV (SGC or HGC) three times daily or 400 mg twice daily in combination with 400 mg of RTV twice daily were included. Each patient was switched to 1000 mg of SQV SGC twice daily in combination with 100 mg of RTV twice daily. After 14 days, the patients came to the hospital for assessment of a pharmacokinetic profile during 12 hours. Patients were randomized to receive a high-fat (+/-45 g of fat) or normal (+/-20 g of fat) breakfast. After 7 days, a second pharmacokinetic profile was assessed after ingestion of the drugs with the alternate breakfast. A noncompartmental pharmacokinetic method was used to calculate the area under the plasma concentration versus time curve (AUC0-12h), the maximum plasma concentration (Cmax), the plasma trough concentration (C12h), and the elimination half-life in plasma (t1/2). The obtained pharmacokinetic parameters were compared with those of 12 patients using SQV HGC (400 mg twice daily) in combination with RTV (400 mg twice daily).

RESULTS

The median values of the pharmacokinetic parameters for SQV SGC (1000 mg twice daily, normal breakfast) were: AUC0-12h, 18.84 h*mg/L; Cmax, 3.66 mg/L; C12h, 0.40 mg/L; and t1/2, 3.0 hours. The median values of the pharmacokinetic parameters for SQV HGC (400 mg twice daily, normal breakfast) were: AUC0-12h, 6.99 h*mg/L; Cmax, 1.28 mg/L; C12h, 0.23 mg/L; and t1/2, 3.9 hours. The exposure to SQV in the dosing regimen of 1000 mg twice daily in combination with 100 mg of RTV twice daily was significantly higher than the exposure to SQV in a dosing regimen of 400 mg twice daily in combination with 400 mg of RTV twice daily. The pharmacokinetic parameters of SQV SGC in the dosing regimen of 1000 mg twice daily in combination with 100 mg of RTV twice daily were not significantly different after ingestion of a high-fat or normal breakfast (p >.35).

CONCLUSIONS

The combination of 1000 mg of SQV SGC twice daily and 100 mg of RTV twice daily resulted in a higher exposure to SQV compared with the exposure to SQV obtained when SQV is used in the 400 mg/400 mg twice-daily combination with RTV. In this small number of patients, no significant differences in exposure were seen after ingestion of either a normal or high-fat breakfast. From a pharmacokinetic perspective, the combination of 1000 mg of SQV SGC twice daily and 100 mg of RTV twice daily seems to be a good option for further clinical evaluation.

Development of drug resistance in patients receiving combinations of zidovudine, didanosine and nevirapine

OBJECTIVE

To evaluate the development of phenotypic and genotypic resistance to zidovudine, didanosine and nevirapine as a function of the virologic response to therapy in a group of drug-naive individuals receiving various combinations of these agents.

DESIGN

All patients were enrolled in a double-blind controlled randomized trial (the INCAS study) and were selected for detailed resistance studies based on specimen availability and virologic response.

METHODS

Within the three study groups (zidovudine/nevirapine, zidovudine/didanosine or zidovudine/nevirapine/didanosine), 16, 19 and 24 patients, respectively, had evaluable baseline isolates and remained in the study > 24 weeks. Phenotypic resistance to all three drugs was evaluated using the VIRCO recombinant virus assay. Genotypic sequencing was done on selected specimens from patients receiving zidovudine/nevirapine/didanosine.

RESULTS

After 24 weeks, all available isolates taken from patients receiving nevirapine were resistant to this agent, while 18/21 (86%) patients receiving triple therapy carried such isolates at 30--60 weeks. At 24 weeks, zidovudine resistance developed in 4/40 isolates but was more frequent after 30--60 weeks, especially in patients on two drugs. The degree of zidovudine resistance (rise in concentration required for 50% inhibition) appeared lower in the triple therapy group compared with zidovudine/didanosine (P = 0.0004). All nevirapine-resistant isolates that were sequenced carried at least one mutation associated with resistance, most often K103N and/or Y181C.

CONCLUSION

The use of highly active drug therapies may be associated with a beneficial effect on the development of antiretroviral drug resistance. The characteristics of virologic suppression that must be maintained to avoid resistance are currently being studied in hypothesis-driven clinical trials.

The steady-state pharmacokinetics of efavirenz and nevirapine when used in combination in human immunodeficiency virus type 1-infected persons

The steady-state pharmacokinetics of efavirenz and nevirapine, when used in combination to treat human immunodeficiency virus type 1 (HIV-1)-infected subjects, were investigated. HIV-1-infected persons who had used efavirenz (600 mg once daily) for > or =2 weeks were eligible for study inclusion. The plasma pharmacokinetics of efavirenz were determined over 24 h. Subsequently, nevirapine (400 mg once daily) was added to the regimen. After 4 weeks, the pharmacokinetics of efavirenz and nevirapine were assessed over 24 h. The differences between the pharmacokinetic parameters of efavirenz with and without nevirapine were analyzed, and the pharmacokinetics of nevirapine were compared with those in historical control patients. The exposure to efavirenz when combined with nevirapine was significantly decreased by 22% (area under the plasma concentration vs. time curve), 36% (minimum plasma concentration), and 17% (maximum plasma concentration). Nevirapine pharmacokinetics appear to be unaffected by coadministration of efavirenz, compared with data from historical control patients.

T cell expansions in lymph nodes and peripheral blood in HIV-1-infected individuals: effect of antiretroviral therapy

OBJECTIVE

To evaluate dynamics in CD8 T cell expansions during highly active antiretroviral therapy (HAART).

DESIGN

Various T cell subsets were isolated from blood and lymph nodes and analysed for T cell receptor (TCR) diversity.

METHODS

TCR complementarity determining region 3 (CDR3) spectratyping and single-strand conformation polymorphism (SSCP) analyses were performed in combination with sequencing to assess clonality of the subsets.

RESULTS

Strongly skewed CDR3 patterns in total CD8 cells and the CD8 subsets CD45RO+CD27+ and CD45RO-CD27+ showed substantial dynamics in dominant CDR3 sizes, resulting in relative improvement of CDR3 size diversity in the first months of therapy. During sustained treatment, TCR diversity changed only moderately. SSCP profiles confirmed oligoclonality of TCR CDR3 perturbations. Various dominant CDR3 sizes for CD4 and CD8 T cells present in lymph nodes, but not in peripheral blood mononuclear cells, before the start of therapy emerged in peripheral blood early during therapy.

CONCLUSIONS

HAART induces substantial changes in CD8 TCR diversity, eventually resulting in improvement of the repertoire. Clonal expansions observed in lymph nodes before therapy were observed in peripheral blood after therapy, suggesting that recirculation of CD4 and CD8 T cells from lymph nodes contributes to the early T cell repopulation. Decreased immune activation and possibly naive T cell regeneration subsequently decreased clonal expansions and perturbations in the CD8 TCR repertoire.

High exposure to nevirapine in plasma is associated with an improved virological response in HIV-1-infected individuals

OBJECTIVE

To explore relationships between exposure to nevirapine and the virological response in HIV-1-infected individuals participating in the INCAS trial.

METHODS

The elimination rate constant of plasma HIV-1 RNA (k) was calculated during the first 2 weeks of treatment with nevirapine, zidovudine and didanosine in 51 antiretroviral-naive HIV-1-infected patients. The relationships between the value of k, the time to reach an undetectable HIV-1 RNA concentration in plasma (< 20 copies/ml) and the success of therapy after 52 weeks of treatment as dependent variables and the exposure to nevirapine, baseline HIV-1 RNA and baseline CD4 cell count as independent variables, were explored using linear regression analyses, proportional hazard models and logistic analyses, respectively.

RESULTS

The value of k for HIV-1 RNA in plasma was positively and significantly associated with the mean plasma nevirapine concentration during the first 2 weeks of therapy (P = 0.011) and the baseline HIV-1 RNA (P = 0.008). Patients with a higher exposure to nevirapine reached undetectable levels of HIV-1 RNA in plasma more rapidly (P = 0.03). From 12 weeks on, the median nevirapine plasma concentration was significantly correlated with success of therapy after 52 weeks (P < 0.02).

CONCLUSIONS

A high exposure to nevirapine (in a twice daily regimen) is significantly associated with improved virological response in the short as well as in the long term. These findings suggest that optimization of nevirapine concentration might be used as a tool to improve virological outcome in (antiretroviral-naive) patients treated with nevirapine.

Saliva as an Alternative Body Fluid for Therapeutic Drug Monitoring of the Nonnucleoside Reverse Transcription Inhibitor Nevirapine

The objective of this study was to evaluate the applicability of saliva as an alternative body fluid for therapeutic drug monitoring of nevirapine. The pharmacokinetics of nevirapine in plasma and saliva during a dosing interval was assessed in HIV-1-infected patients taking nevirapine (200 mg twice daily) to explore the relation between the concentration of nevirapine in plasma and saliva. To validate the anticipated relationship prospectively, single, paired plasma and saliva samples were obtained from nevirapine-treated HIV-1-infected outpatients. The plasma nevirapine concentration was strongly correlated with the salivary concentration. The mean saliva/plasma concentration ratio was 0.51 and was independent of the time after ingestion. Salivary nevirapine concentrations were used to estimate the corresponding plasma concentrations for 31 outpatients. Compared with the true plasma concentrations, the estimated concentrations were biased by -4.2%, with a precision of 13.3%. These data show a strong correlation between the salivary and plasma concentrations of nevirapine at a dosage of 200 mg twice daily. This relation has been validated prospectively, and the prediction of plasma concentrations was accurate and precise. Therefore, the authors conclude that saliva can be a useful body fluid for therapeutic drug monitoring of nevirapine.

A randomized, open-label, comparative trial of zidovudine plus lamivudine versus zidovudine plus lamivudine plus didanosine in antiretroviral-naive HIV-1-infected Thai patients

OBJECTIVE

To assess the efficacy and tolerability of a triple nucleoside reverse transcriptase inhibitor combination of zidovudine, lamivudine, and didanosine therapy.

DESIGN

A randomized open-label trial.

PATIENTS

Antiretroviral-naive HIV-infected patients with CD4+ cell counts of 100 to 500 cells/microl.

METHODS

A total of 106 patients were randomly assigned to 300 mg of zidovudine (200 mg for body weight <60 kg) twice daily plus 150 mg of lamivudine twice daily plus 200 mg of didanosine (125 mg for body weight <60 kg) twice daily (n = 53) or to zidovudine plus lamivudine (n = 53) for 48 weeks.

MAIN OUTCOME MEASURES

Degree and duration of reduction of HIV-1 RNA load and increase in CD4+ cell counts from baseline and development of drug-related toxicities.

RESULTS

At 48 weeks, triple drug therapy showed greater declines in plasma HIV-RNA levels from the beginning of treatment than double drug therapy (1.86 vs. 1.15 log10 copies/ml, respectively; p <.001). The proportions of patients with HIV-RNA <50 copies/ml in an intention-to-treat analysis were 54.7% (29 of 53 patients) and 11.3% (6 of 53 patients) in the triple and double drug therapy, respectively (p =.001). There was no significant difference in increase of CD4 count.

CONCLUSION

Triple drug therapy with zidovudine, lamivudine, and didanosine was significantly more effective in inducing sustained immunologic and virologic responses than the double combination of zidovudine and lamivudine.

OKT3 and IL-2 treatment for purging of the latent HIV-1 reservoir in vivo results in selective long-lasting CD4+ T cell depletion

Activation of resting T cells has been proposed to purge the reservoir of HIV-1-infected resting CD4+ T cells. We therefore treated three HIV-1-infected patients on antiretroviral therapy with OKT3, a CD3 monoclonal antibody, and recombinant human IL-2. Here we report the profound and partially long-lasting host responses induced by the OKT3 and IL-2 treatment. OKT3/IL-2 induced a strong but transient release of plasma cytokines and chemokines. The percentage CD4+ and CD8+ cells in the blood expressing the activation marker CD38 transiently increased to almost 100%, and in lymph nodes we "observed" a 10-fold increase in the number of dividing Ki67+ cells and increased numbers of apoptotic cells. Following OKT3/IL-2 treatment, a long-lasting depletion of CD4+ cells in the peripheral blood and lymph nodes occurred, suggesting the physical deletion of these cells. Increases in CD4+T cell numbers during the two year followup period were due mainly to increased memory cell numbers. CD8+ cells were also depleted in the blood, but less severely in lymph nodes, and returned to baseline levels within several weeks.

Concentrations of human immunodeficiency virus type 1 (HIV-1) RNA in cerebrospinal fluid after antiretroviral treatment initiated during primary HIV-1 infection

In 6 patients with primary human immunodeficiency virus type 1 (HIV-1) infection, concentrations of HIV-1 RNA and beta(2)-microglobulin were monitored in cerebrospinal fluid (CSF) and in plasma during antiretroviral therapy. Four patients had neurological symptoms. At baseline, the CSF of 5 patients had detectable levels of HIV-1 RNA (median, 3.68 log(10) copies/mL; range, <2.60-5.67 log(10) copies/mL), and the CSF of 3 patients had elevated levels of beta(2)-microglobulin. After 8 weeks of treatment, the median concentrations of HIV-1 RNA in CSF had decreased to <2.60 log(10) copies/mL (range, <1.60-3.00 log(10) copies/mL; P=.04) and in plasma to 3.07 log(10) copies/mL (range, 2.57-3.79 log(10) copies/mL; P=.03). Median concentration of beta(2)-microglobulin in CSF had decreased to 1.2 mg/L (range, 0.9-1.7 mg/L; P=.06) and, in plasma, to 1.7 mg/L (range, 1.1-2.2 mg/L; P=.03). After 48 weeks, HIV-1 RNA concentrations in 1 patient were still 1.97 log(10) copies/mL in CSF and 1.51 log(10) copies/mL in plasma, although beta(2)-microglobulin concentrations in CSF and plasma had normalized after 8 weeks.

A retrospective, cohort-based survey of patients using twice-daily indinavir + ritonavir combinations: pharmacokinetics, safety, and efficacy

OBJECTIVE

To describe the pharmacokinetics, safety, and efficacy of twice-daily indinavir + ritonavir regimens

DESIGN

A cohort-based survey of HIV-infected patients who either used indinavir 800 mg + ritonavir 100 mg twice daily or indinavir 400 mg + ritonavir 400 mg twice daily.

METHODS

Data were extracted from a database of samples sent to our laboratory for measurement of indinavir + ritonavir plasma concentrations. Patient characteristics, safety, and efficacy measurements were collected by retrospective chart review.

RESULTS

100 Patients using 800-mg indinavir + 100-mg ritonavir twice daily and 32 patients using 400-mg indinavir + 400-mg ritonavir twice daily were eligible. Median peak and trough concentrations of indinavir were 6.8 and 0.77 mg/L in the 800/100 group and 2.6 and 0.45 mg/L in the 400/400 group. The most frequently found side effects were nausea and vomiting, which occurred in 22.1% and 34.9% of the patients in the 800/100 and the 400/400 groups, respectively. Viral load data were analyzed for patients who switched from 800-mg indinavir three times daily to one of the indinavir + ritonavir twice daily regimens. At the time of switch 63% (800/100 group) and 60% (400/400 group) had an undetectable viral load and this increased to 77% and 70%, respectively, during follow-up. Patients who switched to the 400/400 group discontinued treatment more frequently than patients who switched to the 800/100 group (70% vs. 26%, p =.008).

CONCLUSIONS

Indinavir + ritonavir regimens show improved pharmacokinetic properties, allowing twice-daily dosing with food. Clinical data suggest that safety and efficacy is at least as good as with indinavir three-times-daily regimens without ritonavir. Prospective, comparative trials are needed to properly assess the role in HIV therapy of these twice-daily indinavir + ritonavir regimens.

Durable HIV-1 suppression with indinavir after failing lamivudine-containing double nucleoside therapy: a randomized controlled trial

OBJECTIVE

To assess the durability of the antiretroviral effect in plasma and cerebrospinal fluid (CSF) of antiviral therapy intensification, produced by the addition of indinavir from week 12 onwards to the original regimen of zidovudine/lamivudine or stavudine/lamivudine, after 72 weeks of follow-up using an ultrasensitive HIV-1 RNA assay. To assess CSF concentrations of indinavir at week 48.

DESIGN

In a prospectively, randomized, open, single-centre study, antiretroviral-naive patients (CD4 cell count > or =200 cells/microl and a plasma HIV-1 RNA level 10,000 copies/ml) were assigned to a combination of zidovudine/lamivudine or stavudine/lamivudine. Indinavir could be added to the double nucleoside analogue regimen from week 12 or thereafter in case the plasma HIV RNA level was insufficiently suppressed (>500 copies/ml).

RESULTS

Forty-seven patients were enrolled (23 stavudine/lamivudine and 24 zidovudine/lamivudine), of whom 33 completed a follow-up of 72 weeks. Indinavir was added in 89% (42/47) of the patients. Only one discontinuation occurred due to virological failure. At week 72, the median plasma HIV-1 RNA levels in the zidovudine/lamivudine group had decreased from 4.80 log10 copies/ml to <500 copies/ml in 100% of patients and <50 copies/ml in 86.6% of the patients. In the stavudine/lamivudine group the plasma HIV-1 RNA decreased from 4.98 log10 copies/ml at baseline to <500 copies/ml in 100% of patients and <50 copies/ml in 66.7% of the patients. On an intent-to-treat basis these figures were 54.2 and 52.2% for zidovudine/lamivudine and stavudine/lamivudine, respectively, for the 50 copies/ml assay. The median CD4 cell count increased from 315 cells/microl, with 150 cells/microl in the zidovudine/lamivudine arm, and from 290 cells/microl, with 310 cells/microl in the stavudine/lamivudine arm (P=0.0001). However, the percentage of CD4 cells did not differ in each group. In the zidovudine/lamivudine group 9/10 and 5/5, and in the stavudine/lamivudine group 11/11 and 6/6 had a CSF HIV-1 RNA level <50 copies/ml at week 12 and 48, respectively. The CSF indinavir concentration ranged from 50 to 170 ng/ml.

CONCLUSION

The long-term HIV-1 suppression observed in this study is remarkable, as adding a single antiretroviral agent to a failing regimen goes against current notions of adequate therapy.