Patient registries serve to overcome the research limitations inherent in the study of rare diseases, where patient numbers are typically small. Despite the value of real-world data collected through registries, adequate design and maintenance are integral to data quality. We aimed to describe an overview of the challenges in design, quality management, and maintenance of rare disease registries.A systematic search of English articles was conducted in PubMed, Ovid Medline/Embase, and Cochrane Library. Search terms included “rare diseases, patient registries, common data elements, quality, hospital information systems, and datasets”. Inclusion criteria were any manuscript type focused upon rare disease patient registries describing design, quality monitoring or maintenance. Biobanks and drug surveillances were excluded.A total of 37 articles, published between 2001 and 2021, met the inclusion criteria. Patient registries covered a wide range of disease areas and covered multiple geographical locations, with a predisposition for Europe. Most articles were methodological reports and described the design and setup of a registry. Most registries recruited clinical patients (92%) with informed consent (81%) and protected the collected data (76%). Whilst the majority (57%) collected patient-reported outcome measures, only few (38%) consulted PAGs during the registry design process. Few reports described details regarding quality management (51%) and maintenance (46%).Rare disease patient registries are valuable for research and evaluation of clinical care, and an increasing number have emerged. However, registries need to be continuously evaluated for data quality and long-term sustainability to remain relevant for future use.

This retrospective study examines the outcomes of sclerotherapy in children with (veno)lymphatic malformations who received sclerotherapy between 2011 and 2016 (116 children, 234 procedures). Complication severity was classified using the Society of Interventional Radiology classification. Clinical response was rated on a scale of 0 (no change) to 3 (good improvement). The sclerosants used were bleomycin (n = 132; 56%), lauromacrogol (n = 42; 18%), doxycycline (n = 15; 6%), ethanol (n = 12; 5%), or a combination (n = 33; 14%). Four major and 25 minor complications occurred without significant differences between the agents. The median response rate per procedure was 2—some improvement—for all sclerosants. However, in pure LMs (67%), bleomycin and a combination of agents resulted in the best clinical response. On patient level, all had some or good clinical response. Mixed macrocystic and microcystic lesions showed a significantly lower clinical response (median 2 versus 3; p = 0.023 and p = 0.036, respectively) and required significantly more procedures (median 2 versus 1; p = 0.043 and p = 0.044, respectively) compared with lesions with one component.Conclusion: Sclerotherapy for (V)LMs in children is safe and effective. Bleomycin is the most frequently used agent in this clinic and seemed most effective for pure LMs. Mixed macrocystic and microcystic lesions are most difficult to treat effectively. What is Known:• A variety of agents can be used for sclerotherapy of lymphatic malformations in children.• Macrocystic lesions have favorable outcomes compared with microcystic and mixed lesions. What is New:• Bleomycin and a combination of agents seem to be most effective to treat lymphatic malformations in children.• Mixed macrocystic and microcystic lesions are more difficult to treat effectively compared with lesions with either one of these components.

Anorectal malformations (ARM) are a group of rectal and anal birth defects with a European prevalence of about 1 in 2500–5000 live births^1–4. These rare and complex conditions require highly specialized reconstructive surgery in early life, often with a temporary defunctioning stoma^5–7. ARM are associated with other organ anomalies in 58–78% of patients; therefore, all ARM newborns should be screened for associated anomalies^2,5,8–11. The introduction of posterior sagittal anorectoplasty has improved the management of ARM in recent decades¹². Nevertheless, problems with bowel function can remain throughout adulthood and compromise quality of life^13–20.