This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record.
1. Trial at a Glance
AASK was a randomized, double-masked phase 3 treatment trial studying blood pressure targets and antihypertensive approaches among participants with hypertensive nephrosclerosis and chronic renal insufficiency.
| Feature | AASK |
|---|---|
| Condition | Hypertensive Nephrosclerosis; Chronic Renal Insufficiency |
| Phase | Phase 3 |
| Sponsor | National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) |
| Sponsor type | NIH |
| Allocation | Randomized |
| Design model | Factorial |
| Masking | Double |
| Primary purpose | Treatment |
2. Clinical Question
Population
Patients with hypertensive nephrosclerosis and chronic renal insufficiency.
Intervention
Blood pressure target strategies and antihypertensive medication strategies including ramipril, amlodipine, and metoprolol.
Comparator
Alternative blood pressure goal and antihypertensive treatment strategies within the randomized factorial design.
Primary question
How do treatment strategies affect the rate of change in GFR over follow-up?
3. Trial Design
1094 participants
6 arms
Blood pressure and medication strategies
GFR slope assessment
1995-02-01
2001-09-30
| Intervention | Description |
|---|---|
| MAP goal | Less than or equal to 92 mm Hg |
| MAP goal | 102-107 mm Hg |
| Ramipril | Drug intervention |
| Amlodipine | Drug intervention |
| Metoprolol | Drug intervention |
4. Endpoints
| Endpoint | Definition | Time frame |
|---|---|---|
| Rate of change in GFR | GFR slope was determined separately during the first 3 months after randomization (acute phase) and during the remainder of follow-up (chronic phase). | Up to 3 years |
5. Planned Analysis
The registry identifies the rate of change in GFR as the primary endpoint. GFR slope endpoints are commonly analyzed using longitudinal methods that estimate the trajectory of kidney function over time, separating early treatment-related changes from longer-term trends.
6. Statistical Methodology
Factorial trial design
A factorial design evaluates more than one intervention dimension within the same randomized framework. This approach can allow investigators to study multiple treatment factors efficiently while preserving randomized comparisons.
Longitudinal analysis of GFR slope
The primary endpoint focuses on the rate of change rather than a single kidney function measurement. A slope-based analysis summarizes whether kidney function declines faster or slower over the observation period.
GFR change over time = baseline kidney function + time trend + treatment effects + variability
The acute and chronic phases represent different portions of the follow-up trajectory.
7. Statistical Methods Explained
Why analyze GFR slope instead of one final measurement?
A slope uses repeated measurements and describes the pattern of kidney function change. This can provide more information than comparing only an endpoint value.
Why separate acute and chronic phases?
The registry defines the first 3 months after randomization as an acute phase and the remaining follow-up as a chronic phase. Separating these periods recognizes that early changes may differ from longer-term progression.
What does a factorial design contribute?
A factorial design allows multiple randomized comparisons within a single study structure. Interpretation depends on the prespecified design and assumptions regarding interactions between factors.
Why is randomization important?
Randomization helps balance measured and unmeasured characteristics between treatment groups, supporting unbiased comparisons of assigned strategies.
Why does masking matter?
Double masking can reduce the influence of expectations or knowledge of treatment assignment on participant behavior, clinical management, and outcome assessment.
Why are longitudinal methods useful?
Repeated measurements contain information about individual trajectories. Statistical models can separate overall trends from measurement variability.
8. Limitations
- Registry reporting: ClinicalTrials.gov does not report posted efficacy estimates or confidence intervals for this record.
- Endpoint complexity: GFR slope interpretation depends on assumptions about repeated measurements and follow-up patterns.
- Factorial interpretation: Multiple intervention factors require careful consideration of interaction effects.
- Generalizability: Applicability depends on whether studied participants resemble other populations with chronic renal insufficiency.
9. Why This Trial Matters Statistically
| Concept | How it appears in AASK |
|---|---|
| Randomization | Randomized phase 3 treatment comparison |
| Factorial design | Six-arm study evaluating multiple intervention strategies |
| Longitudinal analysis | Rate of change in GFR over time |
| Phase-specific modeling | Acute and chronic GFR slope periods |
| Clinical endpoints | Kidney function trajectory rather than a single measurement |
10. Related Tutorials
Learn more about the methods used in this trial: