Detailed Instructions: Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Problem:Context: Several aspects of renoprotection by angiotensin-converting enzyme inhibitors (ACEi) in IgA nephropathy (IgAN) are poorly defined: factors affecting responsiveness, role of proteinuria components and histological lesions, and criteria to identify patients who may benefit from ACEi.', 'In an observational study of 140 IgAN patients (follow up 62 +/- 36 months), 73 untreated and 67 ACEitreated for 53 +/- 28 months, 9 baseline risk factors (RFs) (blood pressure, serum creatinine, proteinuria/day, fractional excretion of IgG [FEIgG] and alpha1-microglobulin, global and segmental [SS] glomerular sclerosis, tubulointerstitial damage and arteriolar hyalinosis [AH] score), each divided into 2 subgroups according to a cutoff with the highest sensitivity and specificity for progression, were evaluated for ability to predict renoprotection. Primary end point: end-stage renal disease (ESRD) and doubling of serum creatinine (sCr); secondary end point: increase >or=25% of sCr with last sCr >or=1.58 mg/dL; total progression: sum of end points.', 'Patients with RFs below cutoffs did not benefit from ACEi. All clinical and proteinuric and 2 histological RFs (SS, AH score) with values above cutoffs showed significant reduction of progression in ACEitreated vs. untreated patients; FEIgG showed the highest prediction of renoprotection: ESRD/sCrx2: 20% vs. 62% (p=0.0004); total progression: 40% vs. 85% (p=0.0003). By multivariate analysis, independent predictors of progression were FEIgG, sCr and no ACEi treatment. Proteinuria reduction from -100% to -30%, spontaneous or after ACEi treatment, did not affect progression in treated vs. untreated patients (19% vs. 13%, p=0.85). Patients with proteinuria increased or reduced <30% showed a reduction of total progression if ACEi-treated (15% vs. 77%, p=0.0002). Presence of 1 clinical or proteinuric RF above the cutoff may be a criterion to identify patients who may benefit from ACEi.
Answer: Renoprotection by ACEi is a multifactorial phenomenon: the best predictor of renoprotection is FEIgG, a marker of disruption of glomerular barrier to proteins; renoprotection depends not only on ability to reduce proteinuria, but probably also on antiinflammatory and antifibrotic activity.
Solution:
Is fractional urinary excretion of IgG the most powerful predictor of renoprotection by ACE inhibitors in IgA nephropathy?