Key considerations in the design, conduct, analysis, and interpretation of observational studies in dialysis

In this review, key considerations in the design, conduct, and analysis of observational studies in dialysis research are explored in a unique patient population for which interventional trials are challenging and limited.

The use of target trial emulation is increasing and provides a conceptual framework for the design of observational studies. A target trial is a hypothetical trial that would be conducted to answer a research question. It requires investigators to ask a clinically relevant question and then specify eligibility criteria, the treatment strategies that will be compared, the follow-up period, outcomes of interest, and the causal contrast (intention-to-treat vs. per-protocol analysis). The protocol for an observational study is then created to mirror the target trial. In doing so, the question is clear, bias is reduced, and underlying assumptions are made transparent. Illustrative examples are used to highlight common pitfalls in dialysis research.

In conclusion, randomized controlled trials are not always feasible or even the ideal approach for answering certain questions. However, observational studies are challenging and require careful planning and execution to ensure robust, unbiased results. Target trial emulation provides a blueprint to improve the quality of observational study design.