I read the article, "Referral of Children to Specialists in the United States and the United Kingdom [UK]"1 with interest. I applaud the authors' long-standing and continued dedication to understanding children's access to and use of specialty services in the United States, a poorly understood issue.
I appreciate the authors' restraint in using their findings to determine whether subspecialty use rates in the United States are too high or those in the UK are too low. I do wonder, however, to what extent the higher treatment morbidity index in the UK may result from insufficient access to subspecialty care. Without more detail as to how this index is measured, it is difficult to know if there is a potential for reverse causation.
Mayer ML. Subspecialty Care Use Rates: Reverse Causation and Generalizability Issues. Arch Pediatr Adolesc Med. 2003;157(10):1032-1033. doi:10.1001/archpedi.157.10.1032-a