The longitudinal care cascade for hypertension: a clinic-based study of people with and without HIV in South Africa

This longitudinal study in South Africa reveals that despite frequent health system contact, people living with HIV experience significantly lower hypertension diagnosis rates and higher rates of treatment regression and loss of blood pressure control compared to those without HIV, highlighting critical gaps in integrated chronic disease management.

The Gist

Imagine South Africa's healthcare system as a massive, busy train station. Two main groups of passengers are trying to get to the same destination: good health.

One group is traveling with a specific, well-known ticket: HIV. Because they have this ticket, they visit the station (the clinic) very frequently to pick up their HIV medication.
The other group is traveling without that specific ticket: people without HIV. They only come to the station when they feel sick or need a check-up.

Both groups are at risk of a different problem called Hypertension (high blood pressure). Think of high blood pressure as a "leaky pipe" in your body's plumbing. If you don't fix it, it can burst and cause serious damage later.

This study looked at how well the station helps both groups find, fix, and keep that leaky pipe under control over time. Here is what they found, using some simple comparisons:

1. The "Leaky Pipe" is More Common in the "No-Ticket" Group

Surprisingly, the study found that people without HIV were actually more likely to have high blood pressure to begin with (about 53%) compared to those with HIV (about 29%).

• The Analogy: It's like finding that the people who don't visit the station often are actually the ones with the most broken pipes. The people who visit the station every month (PLHIV) seem to have fewer leaks initially.

2. The "Diagnosis Gap": Missing the Leak

Even though people with HIV visit the clinic constantly, the study found a major problem: they often don't know they have high blood pressure.

• The Analogy: Imagine a mechanic who checks your car every week for a specific engine part (HIV meds) but completely ignores the tires (blood pressure). The study found that people with HIV were 3.4 times more likely to be driving around with a flat tire they didn't know about, compared to people without HIV. Because they are so focused on their HIV treatment, the blood pressure issue slips through the cracks.

3. The "Control Struggle": Keeping the Pressure Down

For the people who did get diagnosed and started treatment, the people with HIV had a harder time keeping their blood pressure under control.

• The Analogy: It's like two gardeners trying to water a plant. The gardener without HIV is able to keep the plant perfectly watered. The gardener with HIV, even though they are there every day, struggles to keep the plant from wilting. They are less likely to reach the "green zone" of perfect health.

4. The "Slippery Slope": Falling Back

This is the most critical finding. The study tracked people over time and saw that people with HIV were much more likely to fall backward in their treatment.

• The Analogy: Imagine climbing a ladder to fix a roof.
  • People without HIV climb up, fix the roof, and stay there.
  • People with HIV climb up, but then they slip down. They might stop taking their blood pressure meds, or their blood pressure might spike again even while they are on meds.
  • The study found that people with HIV were 50% more likely to slip from "treated" back to "untreated," and more likely to slip from "controlled" back to "uncontrolled."

The Big Takeaway

The researchers concluded that even though people with HIV are in the healthcare system constantly, the system is treating them like they only have one problem (HIV), ignoring the second problem (blood pressure).

The Solution: The clinics need to stop looking at the "HIV ticket" and start looking at the whole person. They need an integrated model—like a mechanic who checks the engine and the tires at the same time. If they don't fix how they manage these two conditions together, people with HIV will keep slipping off the ladder, and their "leaky pipes" will never get truly fixed.

Technical Summary

Technical Summary: The Longitudinal Care Cascade for Hypertension in South Africa

1. Problem Statement

South Africa faces a significant dual burden of disease characterized by high prevalence rates of both HIV and hypertension (HTN). While the management of HIV is well-established within the public health system, there is a critical lack of longitudinal evidence regarding how individuals navigate the hypertension care cascade over time. Specifically, there is insufficient data comparing the progression and regression patterns of HTN management between People Living with HIV (PLHIV) and People Not Living with HIV (PNLHIV). Understanding these dynamics is essential to identify systemic gaps and develop integrated chronic disease management strategies.

2. Methodology

• Study Design: A longitudinal secondary analysis of data derived from the iHEART-SA trial.
• Setting: Nine public primary healthcare clinics in Johannesburg, South Africa.
• Timeline: Data collection occurred between August 2022 and May 2024, with follow-up extending through May 2025.
• Population: 23,855 adults (≥18 years) with a known HIV status and completed medical file reviews.
  • Demographics: 78.5% were PLHIV (median age 42, 69% female).
• Analytical Approach: The study assessed movement across the HTN care cascade, specifically measuring:
  • Progression: Movement from undiagnosed to diagnosed, treated, and controlled states.
  • Regression: Movement backward in the cascade (e.g., from treated to untreated, or controlled to uncontrolled).
• Statistical Measures: Adjusted Risk Ratios (aRR) with 95% Confidence Intervals (CI) were used to compare outcomes between PLHIV and PNLHIV.

3. Key Contributions

This study provides one of the first longitudinal assessments of the hypertension care cascade in a setting with high HIV prevalence. Its primary contributions include:

• Comparative Longitudinal Analysis: It moves beyond cross-sectional snapshots to track how patients move (or fail to move) through the care continuum over time.
• HIV-Status Stratification: It explicitly isolates the impact of HIV status on HTN management, challenging the assumption that frequent contact with HIV services automatically translates to better non-communicable disease (NCD) outcomes.
• Identification of Regression: It highlights "regression" (loss of control or treatment discontinuation) as a critical metric, revealing that PLHIV are more prone to falling out of effective care than PNLHIV.

4. Key Results

• Prevalence: Overall, 34.4% of participants had high blood pressure. Prevalence was significantly higher in PNLHIV (53.5%) compared to PLHIV (29.3%) ($p<0.001$).
• Diagnosis Gap: Despite frequent health system contact, PLHIV were substantially more likely to remain undiagnosed compared to PNLHIV (Adjusted Risk Ratio [aRR] 3.40; 95% CI 3.12–3.71).
• Control Gap: Among those receiving treatment, PLHIV were less likely to achieve blood pressure control (aRR 0.83; 95% CI 0.75–0.91).
• Regression Rates: PLHIV experienced significantly higher rates of cascade regression:
  • Regression to untreated HTN: 29% for PLHIV vs. 19% for PNLHIV (aRR 1.51; 95% CI 1.35–1.70).
  • Loss of BP control: Regression from controlled to uncontrolled BP was higher in PLHIV (aRR 1.12; 95% CI 1.05–1.18).

5. Significance and Implications

The findings underscore a paradox: while PLHIV have high engagement with the health system due to HIV care, this does not guarantee effective hypertension management. The study reveals persistent gaps in longitudinal HTN management within HIV programs, characterized by:

1. Missed Diagnoses: A failure to screen for HTN effectively within HIV clinics.
2. Treatment Instability: Higher rates of treatment discontinuation and loss of control among PLHIV.

Conclusion: The study argues for a shift from siloed care to integrated and targeted chronic care models. To address these gaps, health systems must ensure treatment continuity and sustained blood pressure control specifically tailored to the needs of PLHIV, rather than assuming HIV care infrastructure is sufficient for managing comorbid NCDs.