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Table 2Strength of evidence for prevention of stone recurrence: pharmacological intervention trials

InterventionStone
Recurrence
Type
Number of TrialsNumber of Randomized SubjectsSummary Statistics, RR [95% CI]Risk of Bias*Directness**PrecisionConsistencyEvidence Rating††
Thiazide vs. placebo or controlSymptomatic1511.04 [0.39 to 2.80]mediumdirectimpreciseNAInsufficient
Composite63870.53 [0.41 to 0.68]mediumdirectpreciseconsistentModerate
Radiographic0------Insufficient
Citrate vs. placebo or controlSymptomatic0------Insufficient
Composite42500.25 [0.14 to 0.44]mediumdirectpreciseconsistentModerate
Radiographic1500.95 [0.62 to 1.44]mediumdirectimpreciseNALow
Allopurinol vs. placebo or controlSymptomatic1720.36 [0.11 to 1.19]mediumdirectimpreciseNALow
Composite22040.59 [0.42 to 0.84]mediumdirectpreciseconsistentModerate
Radiographic1721.07 [0.16 to 7.10]mediumdirectimpreciseNAInsufficient
AHA vs. placebo or controlSymptomatic0------Insufficient
Composite0------Insufficient
Radiographic23040.81 [0.18 to 3.66]mediumdirectimpreciseconsistentInsufficient
Magnesium vs. placeboSymptomatic0------Insufficient
Composite1820.65 [0.37 to 1.16]mediumdirectimpreciseNALow
Radiographic0------Insufficient
Thiazide plus citrate vs. thiazideSymptomatic0------Insufficient
Composite11000.94 [0.52 to 1.68]mediumdirectimpreciseNALow
Radiographic0------Insufficient
Thiazide plus allopurinol vs. thiazideSymptomatic0------Insufficient
Composite1500.79 [0.18 to 3.49]mediumdirectimpreciseNAInsufficient
Radiographic0------Insufficient

Abbreviations: CI = confidence intervals; AHA = Acetohydroxamic acid; NA = not applicable; RR = relative risk

*

Risk of bias was rated low, medium, or high based on whether the design and conduct of the studies for a given outcome or comparison indicate good internal validity.

**

Directness indicated whether results reflect a single, direct link between the intervention of interest and the outcome and was rated as either direct or indirect.

Precision indicated the degree of certainty surrounding an effect estimate of a given outcome and was rated either precise or imprecise, with a precise estimate being one that allowed a clinically meaningful conclusion.

Consistency indicated whether the included studies found a similar direction of effect and was rated consistent, inconsistent, or, in cases when only a single study was evaluated, unknown/not applicable.

††

Evidence was rated using the following grades: (1) high confidence indicated that further research is very unlikely to change the confidence in the estimate of effect, meaning that the evidence reflects the true effect; (2) moderate confidence denoted that further research may change our confidence in the estimate of effect and may change the estimate; (3) low confidence indicated that further research is very likely to have an important impact on the confidence in the estimate of effect and is likely to change the estimate, meaning there is low confidence that the evidence reflects the true effect; and 4) insufficient, indicating that the evidence was unavailable or did not permit a conclusion. Examples when evidence is available, but SOE may be graded as insufficient include when there is an unacceptably high risk of bias, or there is a major inconsistency that cannot be explained (e.g., 2 studies with the same risk of bias with opposite results and no clear explanation for the discrepancy). In addition, SOE may be graded as insufficient when data are too imprecise. This may be the case when the 95% CI is so wide that it cannot exclude either a clinically significant benefit or harm (e.g. lower CI bound [left angle bracket]0.5 and upper CI bound >2).

Risk of bias was rated low, medium, or high based on whether the design and conduct of the studies for a given outcome or comparison indicate good internal validity.

Directness indicated whether results reflect a single, direct link between the intervention of interest and the outcome and was rated as either direct or indirect.

Precision indicated the degree of certainty surrounding an effect estimate of a given outcome and was rated either precise or imprecise, with a precise estimate being one that allowed a clinically meaningful conclusion.

Consistency indicated whether the included studies found a similar direction of effect and was rated consistent, inconsistent, or, in cases when only a single study was evaluated, unknown/not applicable.

Evidence was rated using the following grades: (1) high confidence indicated that further research is very unlikely to change the confidence in the estimate of effect, meaning that the evidence reflects the true effect; (2) moderate confidence denoted that further research may change our confidence in the estimate of effect and may change the estimate; (3) low confidence indicated that further research is very likely to have an important impact on the confidence in the estimate of effect and is likely to change the estimate, meaning there is low confidence that the evidence reflects the true effect; and 4) insufficient, indicating that the evidence was unavailable or did not permit a conclusion. Examples when evidence is available, but SOE may be graded as insufficient include when there is an unacceptably high risk of bias, or there is a major inconsistency that cannot be explained (e.g., 2 studies with the same risk of bias with opposite results and no clear explanation for the discrepancy). In addition, SOE may be graded as insufficient when data are too imprecise. This may be the case when the 95% CI is so wide that it cannot exclude either a clinically significant benefit or harm (e.g. lower CI bound [left angle bracket]0.5 and upper CI bound >2).

From: Results

Cover of Recurrent Nephrolithiasis in Adults
Recurrent Nephrolithiasis in Adults: Comparative Effectiveness of Preventive Medical Strategies [Internet].
Comparative Effectiveness Reviews, No. 61.
Fink HA, Wilt TJ, Eidman KE, et al.

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