Meta-analysis as a clinical tool in nephrology

Do meta-analyses in nephrology change the way we treat patients?

There has been an exponential increase in the number of nephrological meta-analyses published, but their relative contribution to the nephrology literature is unclear and their influence on physician behavior and evidence-based patient care is poorly understood. We studied the nephrology literature, point-of-care resources, guidelines, and a questionnaire survey of the New York Society of Nephrology membership to understand the role and perception of meta-analyses in nephrology. We discuss our results in the context of the strengths and limitations of meta-analyses and their relatively limited, albeit increasing influence on published guidelines and on point-of-care references. The results of our practitioner survey and our review of the nephrology literature suggest an increasing influence at the level of the individual practitioner of meta-analyses. This underlines the need to develop a better understanding of the contributions and role of meta-analyses in the literature.

Interferon treatment in hemodialysis patients with chronic hepatitis C virus infection: a systematic review of the literature and meta-analysis of treatment efficacy and harms

BACKGROUND

Hepatitis C virus (HCV) infection is prevalent in patients undergoing hemodialysis and is associated with greater mortality. We determined the efficacy and harms of interferon (IFN) and pegylated IFN (PEG-IFN) treatment of hemodialysis patients with chronic HCV infection and identified factors associated with these outcomes.

STUDY DESIGN

Meta-analysis and meta-regression of randomized controlled trials, uncontrolled trials, and prospective observational studies.

SETTING & POPULATION

Hemodialysis patients with chronic HCV infection.

SELECTION CRITERIA FOR STUDIES

MEDLINE indexed studies since 1966, sample size greater than 10.

INTERVENTION

IFN-based treatment, including PEG-IFN with and without ribavirin.

OUTCOMES

Sustained virological response (SVR) 6 months after treatment, rate of treatment discontinuation caused by adverse events, and factors associated with these outcomes.

RESULTS

20 studies of 459 IFN-treated patients, 3 studies of 38 PEG-IFN-treated patients, and 2 studies of 49 PEG-IFN and ribavirin-treated patients met inclusion criteria. The overall SVR rate was 41% (95% confidence interval [CI], 33 to 49) for IFN and 37% (95% CI, 9 to 77) for PEG-IFN. Treatment discontinuation rates were 26% (95% CI, 20 to 34) for IFN and 28% (95% CI, 12 to 53) for PEG-IFN. SVR was higher with 3 million units (MU) or higher of IFN 3 times weekly, with lower mean HCV RNA, and with lower rates of cirrhosis, HCV genotype 1 or elevated transaminase, but these findings were not statistically significant. Treatment discontinuation rates were greater in studies using larger doses.

LIMITATIONS

Publication bias, few randomized controlled trials, and limitations in generalizability to all hemodialysis patients.

CONCLUSION

IFN treatment of hemodialysis patients results in an SVR rate of 41%. Higher dose, lower mean HCV RNA level, and lower rates of cirrhosis, transaminase level increase, and HCV genotype 1 may be associated with greater SVR rates, but additional studies using individual patient data are needed.

Angiotensin I-converting enzyme gene polymorphism in non-diabetic renal disease

BACKGROUND

The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene determines the concentration of ACE in serum and local tissues. The role of this polymorphism in progressive chronic renal disease is still not fully clear.

METHODS

We analysed the impact of the D/D polymorphism on the rate of decline in renal function in patients with non-diabetic, chronic progressive renal insufficiency. Seventy non-diabetic patients, aged 21-69 years at baseline, with moderately advanced renal insufficiency due to primary chronic renal disease were followed for an average of 3 years with repeated measurements of their glomerular filtration rate (GFR). Their mean GFR at baseline was 41 ml/min/1.73 m(2) body surface area (BSA). The polymerase chain reaction (PCR) amplification method was used to detect the I/D polymorphism of the ACE gene. GFR was measured as the clearance of (51)Cr-EDTA and the individual rate of progression was calculated using linear regression.

RESULTS

The distributions of the genotypes were: D/D 30%, I/D 49%, and I/I 21%. The rates of progression in the three ACE genotype groups were an annual decline in renal function of -4.2 (SD 4.6) ml/minx1.73 m(2) BSA in the D/D group, -2.7 (SD 3. 4) in the I/D group and -1.7 (SD 3.4) in the I/I group (ANOVA P=0. 12). In patients with proteinuria below 3.5 g/24 h, the D/D group had a significantly higher rate of progression than patients with the I allele. The same was found in a separate analysis when only patients with normal apoliprotein B (below 155 mg/dl) levels were analysed. Furthermore, the D/D genotype was a significant predictor of a more rapid decline in renal function in male, but not female, patients.

CONCLUSION

The results in this study in non-diabetic patients with chronic renal disease indicate that the presence of the D allele in the ACE genotype may be of particular importance as a predictor of a high rate of progression in male patients who otherwise do not have a major burden of documented and important prognostic factors for progressive renal insufficiency.

Effect of gender on the progression of nondiabetic renal disease: a meta-analysis

There is previously published evidence that male gender is associated with a more rapid rate of progression of nondiabetic chronic renal disease. However, some investigators have concluded that no such association exists. To help resolve this issue, a meta-analysis was performed using 68 studies that met defined criteria and contained a total of 11,345 patients to evaluate the effect of gender on the progression of nondiabetic chronic renal disease. The results indicate that men with chronic renal disease of various etiologies show a more rapid decline in renal function with time than do women.