# Association of leukocyte count with death in people with HIV: A longitudinal study over 24 years

## TL;DR

High or low white blood cell counts are linked to higher death risk in people with HIV, even when their virus is controlled.

## Contribution

Shows that leukocyte levels predict mortality in HIV patients, independent of other risk factors.

## Key findings

- High leukocyte counts (≥7730/μL) increase mortality risk by 56% in HIV patients.
- Low leukocyte counts (≤4250/μL) also raise mortality risk by 51%.
- High leukocytes are linked to cancer, cardiovascular, and respiratory deaths in HIV patients.

## Abstract

Increased blood leukocytes are associated with all-cause mortality and death from coronary disease and cancer in the general population. Limited information is available in people with HIV.

We analyzed blood leukocytes in 1850 participants of the Swiss HIV Cohort Study who died (2000–2023) and 1850 matched controls (median age at death 52 years, 77% male, 77% with suppressed HIV RNA on antiretroviral therapy). We assessed uni-/multivariable odds ratios (OR) for all-cause mortality, considering major clinical and HIV-related mortality risk factors, leukocytes measured >1 year before death (primary analysis) and in the latest available blood sample, and potential confounders for leukocytes.

Leukocytes showed a U-shaped association with mortality. At a median of 433 (interquartile range [IQR], 396–495) days before death, multivariable-adjusted OR for death in the highest (leukocytes ≥7730/μL) vs. middle quintile (leukocytes 5290–6260/μL) was 1.56 (95% confidence interval, 1.20–2.02). Multivariable-adjusted OR in the lowest (leukocytes ≤4250/μL) vs. middle leukocyte quintile was 1.51 (1.14–2.01). For comparison, death-OR for hypertension, diabetes and current smoking were 1.27 (1.06–1.53), 1.91 (1.41–2.57), and 2.72 (2.14–3.45), respectively. Leukocytosis was uncommon (cases, 4.4% vs. controls, 2.3%; p = 0.004). The effect size of the highest leukocyte quintile increased in the latest blood sample (median 86 [IQR], 43–152 days before death; OR=1.99 [1.44–2.76]). High leukocytes were associated with death from non-AIDS/non-hepatic cancer, cardiovascular, and respiratory causes. Low leukocytes were associated with liver-related death.

High leukocytes, measured >1 year before death and mostly within the normal range, are independently associated with mortality in people with HIV in Switzerland.