Table 1. Items and Grades for Quality Evaluation of the Analytical Epidemiological Studies on the Smoking-Induced Renal Damage in the Generally Healthy Population.
| Grades | |||
|---|---|---|---|
| Items | Good | Fair | Acceptable |
| Selection of subjects | |||
| Definitiona | Recruited from community or workplace with exclusion of preceding primary kidney diseases and DM | Recruited from community or workplace with exclusion of preceding primary kidney diseases | Recruited from community or workplace without any exclusion of preceding diseases |
| Representativeness | Randomized selection from or including 70% or more of the whole population | Not randomized but not arbitrary selection from the whole population | |
| Size of population | 4,000 or more in men and 8,000 or more in women | 400 or more in men and 800 or more in womenb | 100 or more in men and 200 or more in women |
| Duration of observationc | 10 years or longer | 5 years or longer | 2 years or longer |
| Definition of exposure (Smoking status) | Smoker / Exsmoker Never smoker Accumulated dose | Smoker / Exsmoker Never smoker | Smoker /non-smoker |
| Measurement of outcome | |||
| Proteinuria (Albuminuria) | Quantitative measurement | Semiquantitative (dipstick) measurement | |
| Renal function | Actual measurement of GFR or Ccr or Estimation of GFR by a standardized equation | Estimation of Ccr by a CockcroftGault Equation or Measurement of serum creatinine concentration | |
| Statistical analysis | Appropriate methods, Appropriate description | Appropriate methods | |
| Consideration on confounding factorsd | Demographic factors, Anthropometrical factors, Impaired GT and high BP | Demographic factors, Anthropometrical factors | Demographic factors |
Abbreviations: BP, blood pressure; Ccr, creatinine clearance CKD, chronic kidney disease; DM, diabetes mellitus; GFR, glomerular filtration rate; GT, glucose tolerance.
aIn cohort study, the patients with the endpoint CKD should be excluded at the baseline .
bMinimal ample size required to detect the difference in the prevalence of CKD between smokers and nonsmokers.
cRequired item in cohort study.
dAppropriate matching of case and control or applying appropriate multivariate analyses.