physicians for their generous help. Seventeen CQ were created based on questions the committee members had from actual clinical practice. These guidelines were completed owing to the dedication and effort of the physicians who served on the PKD working group. We thank them again for their efforts. (shown separately: 2014 evidence-based PKD clinical guidelines committee) 5. Contents of the guideline Guidelines on four diseases (IgA nephropathy, nephrotic syndrome, RPGN, and PKD) with the same format and structure were drafted by a research group on progressive kidney disorders (led by Seiichi Matsuo) funded by the Ministry of Health, Labour, and Welfare’s research project for overcoming intractable diseases. As described earlier, the first half (chapters 1–4) addresses ADPKD and the second half (chapters 5–8) addresses ARPKD. 6. Evidence Levels and Recommendation Grades Evidence was classified into six levels based on the study design, and was arranged roughly from the most reliable study type (Level 1) to the least reliable (Level 6). These levels do not necessarily represent rigorous scientific standards; they are intended for use as a convenient reference for quickly assessing the significance of various clinical data during the physician’s decision-making process. [Evidence Levels] Level 1: Systematic review/meta-analysis Level 2: At least one randomized controlled trial (RCT) Level 3: A non-RCT Level 4: An analytical epidemiologic study (cohort study or case-control study) or a single-arm intervention study (no controls) Level 5: A descriptive study (case report or case series) Level 6: Opinion of an expert committee or an individual expert, which is not based on patient data However, for a systematic review/meta-analysis, the evidence level was decided based on the designs of the underlying studies. If the underlying study designs were mixed, the lowest level underlying study was used to determine the overall evidence level. For example, a meta-analysis of cohort studies would be Level 4, but the same Level 4 would also be assigned to a meta-analysis including both RCTs and cohort studies. In addition, a decision based on committee consensus was that all subanalyses and post-hoc analyses of RCTs should be categorized at evidence Level 4. Accordingly, it was decided that the evidence level of findings representing the primary endpoints of an RCT would be Level 2, but the evidence level of findings determined via a sub analysis or post-hoc analysis of that RCT would be Level 4. When a statement related to a certain treatment was presented, consideration was given to the level of the evidence serving as the basis of that statement, and a recommendation grade was assigned as outlined below: [Recommendation Grades] Grade A: Strongly recommended because the scientific basis is strong. Grade B: Recommended because there is some scientific basis. Grade C1: Recommended despite having only a weak scientific basis Grade C2: Not recommended because there is only a weak scientific basis Grade D: Not recommended because scientific evidence shows the treatment to be ineffective or harmful. If we found only a weak scientific basis for a certain statement concerning a treatment, the members of the committee discussed the matter and decided on C1 or C2 for the recommendation grade. Thus, discrimination between C1 and C2 statements was based on expert consensus. 7. Issues on the preparation of this guideline (1) Paucity of evidence Little evidence exists for PKD, and only few large clinical studies have been performed globally, apart from a small number in the United States and Europe. For the most part, little evidence substantiates the recommendations in the CQ. In particular, almost no evidence comes from Japan. Whether the results of clinical research from the West can be applied as is to Japan is a question that deserves careful consideration. In creating these guidelines, we strove to ensure that they would not deviate greatly from the clinical practice in Japan. (2) Issues on medical resources In general, the clinical guideline must consider medical resources associated with recommended statements. However, the current guideline did not discuss issues on medical cost; thus medical financial problems did not affect the contents of our guideline. In the next guideline, this point may be included. (3) Guideline reflecting the opinions of patients During the preparation processes of the clinical guideline, we needed to introduce the opinions of patients. However, this time, we unfortunately could not include the opinions of patients. We should refer to the opinions of patients in the next guideline, particularly in the case that the guideline is used for patients. 8. Financial sources and conflict of interest The funds used in creating the guidelines were provided by a research group on progressive kidney disorders funded by the Ministry of Health, Labour, and Welfare’s research project for overcoming intractable diseases. These funds were used to pay for transportation to and from meetings, to rent space for meetings, and for box lunches and snacks. The committee members received no compensation. Everyone involved in creating the guidelines (including referees) submitted conflict-of-interest statements based on academic society rules, which are managed by JSN. Opinions were