A comparison of ad hoc methods to account for non-cancer AIDS and deaths as competing risks when estimating the effect of HAART on incident cancer AIDS among HIV-infected men

The Effect of MSM and CD4+ Count on the Development of Cancer AIDS (AIDS-defining Cancer) and Non-cancer AIDS in the HAART Era

BACKGROUND

The HIV epidemic is increasing among Men who have Sex with Men (MSM) and the risk for AIDS defining cancer (ADC) is higher among them.

OBJECTIVE

To examine the effect of MSM and CD4+ count on time to cancer AIDS (ADC) and noncancer AIDS in competing risks setting in the HAART era.

METHOD

Using Ontario HIV Treatment Network Cohort Study data, HIV-positive adults diagnosed between January 1997 and October 2012 having baseline CD4+ counts ≤ 500 cells/mm3 were evaluated. Two survival outcomes, cancer AIDS and non-cancer AIDS, were treated as competing risks. Kaplan-Meier analysis, Cox cause-specific hazards (CSH) model and joint modeling of longitudinal and survival outcomes were used.

RESULTS

Among the 822 participants, 657 (79.9%) were males; 686 (83.5%) received anti-retroviral (ARV) ever. Regarding risk category, the majority (58.5%) were men who have Sex with men (MSM). Mean age was 37.4 years (SD = 10.3). In the multivariate Cox CSH models, MSM were not associated with cancer AIDS but with non-cancer AIDS [HR = 2.92; P = 0.055, HR = 0.54; P = 0.0009, respectively]. However, in joint models of longitudinal and survival outcomes, MSM were associated with cancer AIDS but not with non-cancer AIDS [HR = 3.86; P = 0.013, HR = 0.73; P = 0.10]. CD4+ count, age, ARV ever were associated with both events in the joint models.

CONCLUSION

This study demonstrates the importance of considering competing risks, and timedependent biomarker in the survival model. MSM have higher hazard for cancer AIDS. CD4+ count is associated with both survival outcomes.

Prognosis in HIV-infected patients with non-small cell lung cancer

Background:

We conducted a population-based study to evaluate whether non-small cell lung cancer (NSCLC) prognosis was worse in HIV-infected compared with HIV-uninfected patients.

Methods:

Using the Surveillance, Epidemiology and End Results (SEER) registry linked to Medicare claims, we identified 267 HIV-infected patients and 1428 similar controls with no evidence of HIV diagnosed with NSCLC between 1996 and 2007. We used conditional probability function (CPF) analyses to compare survival by HIV status accounting for an increased risk of non-lung cancer death (competing risks) in HIV-infected patients. We used multivariable CPF regression to evaluate lung cancer prognosis by HIV status adjusted for confounders.

Results:

Stage at presentation and use of stage-appropriate lung cancer treatment did not differ by HIV status. Median survival was 6 months (95% confidence interval (CI): 5–8 months) among HIV-infected NSCLC patients compared with 20 months (95% CI: 17–23 months) in patients without evidence of HIV. Multivariable CPF regression showed that HIV was associated with a greater risk of lung cancer-specific death after controlling for confounders and competing risks.

Conclusion:

NSCLC patients with HIV have a poorer prognosis than patients without evidence of HIV. NSCLC may exhibit more aggressive behaviour in the setting of HIV.

Baseline kidney function as predictor of mortality and kidney disease progression in HIV-positive patients

BACKGROUND

Chronic kidney disease (CKD) is associated with increased all-cause mortality and kidney disease progression. Decreased kidney function at baseline may identify human immunodeficiency virus (HIV)-positive patients at increased risk of death and kidney disease progression.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

7 large HIV cohorts in the United Kingdom with kidney function data available for 20,132 patients.

PREDICTOR

Baseline estimated glomerular filtration rate (eGFR).

OUTCOMES

Death and progression to stages 4-5 CKD (eGFR <30 mL/min/1.73 m(2) for >3 months) in Cox proportional hazards and competing-risk regression models.

RESULTS

Median age at baseline was 34 (25th-75th percentile, 30-40) years, median CD4 cell count was 350 (25th-75th percentile, 208-520) cells/μL, and median eGFR was 100 (25th-75th percentile, 87-112) mL/min/1.73 m(2). Patients were followed up for a median of 5.3 (25th-75th percentile, 2.0-8.9) years, during which 1,820 died and 56 progressed to stages 4-5 CKD. A U-shaped relationship between baseline eGFR and mortality was observed. After adjustment for potential confounders, eGFRs <45 and >105 mL/min/1.73 m(2) remained associated significantly with increased risk of death. Baseline eGFR <90 mL/min/1.73 m(2) was associated with increased risk of kidney disease progression, with the highest incidence rates of stages 4-5 CKD (>3 events/100 person-years) observed in black patients with eGFR of 30-59 mL/min/1.73 m(2) and those of white/other ethnicity with eGFR of 30-44 mL/min/1.73 m(2).

LIMITATIONS

The relatively small numbers of patients with decreased eGFR at baseline and low rates of progression to stages 4-5 CKD and lack of data for diabetes, hypertension, and proteinuria.

CONCLUSIONS

Although stages 4-5 CKD were uncommon in this cohort, baseline eGFR allowed the identification of patients at increased risk of death and at greatest risk of kidney disease progression.

HIV as an independent risk factor for incident lung cancer

BACKGROUND

It is unclear whether the elevated rate of lung cancer among HIV-infected persons is due to biological effects of HIV, surveillance bias, or excess smoking. We compared the incidence of lung cancer between HIV-infected and demographically similar HIV-uninfected patients, accounting for smoking and stage of lung cancer at diagnosis.

DESIGN

Data from the Veterans Aging Cohort Study Virtual Cohort were linked to data from the Veterans Affairs Central Cancer Registry, resulting in an analytic cohort of 37,294 HIV-infected patients and 75,750 uninfected patients.

METHODS

We calculated incidence rates of pathologically confirmed lung cancer by dividing numbers of cases by numbers of person-years at risk. We used Poisson regression to determine incidence rate ratios (IRRs), adjusting for age, sex, race/ethnicity, smoking prevalence, previous bacterial pneumonia, and chronic obstructive pulmonary disease.

RESULTS

The incidence rate of lung cancer in HIV-infected patients was 204 cases per 100,000 person-years [95% confidence interval (CI) 167-249] and among uninfected patients was 119 cases per 100,000 person-years (95% CI 110-129). The IRR of lung cancer associated with HIV infection remained significant after multivariable adjustment (IRR 1.7; 95% CI 1.5-1.9). Lung cancer stage at presentation did not differ between HIV-infected and uninfected patients.

CONCLUSION

In our cohort of demographically similar HIV-infected and uninfected patients, HIV infection was an independent risk factor for lung cancer after controlling for potential confounders including smoking. The similar stage distribution between the two groups indicated that surveillance bias was an unlikely explanation for this finding.