M.A. Vitale and W.N. Levine reply:
We commend Dr. Schneider for his thoughtful review of our manuscript and careful consideration of factors that may contribute to the increasing frequency and population-based incidence of acromioplasty procedures over the past decade as documented independently by both CPT codes (in the ABOS database) and ICD-9 procedure codes (in the SPARCS database). Dr. Schneider points out that while the incidence of coding of acromioplasty by ICD-9 procedure and CPT codes has increased, this may not necessarily reflect a true increase in the incidence of the procedure over this period. Other reasons to explain the increased coding include the so-called unbundling of procedure codes for shoulder surgery, the increasing pressures for coding documentation by the ABOS, and a growing financial incentive to bill for multiple codes, given decreasing reimbursements from insurers.
We did, however, use a control group for the possible confounder that we are measuring increases in codes rather than in procedures. In Part A, we compared all acromioplasties (open or arthroscopic) as identified by an ICD-9 procedure code with all other orthopaedic procedures as identified by ICD-9 procedure codes performed in hospital or freestanding ambulatory surgery centers on an outpatient basis. In Part B, we compared all arthroscopic acromioplasties as identified by a CPT code with all other orthopaedic surgical procedures identified by CPT codes performed in hospital or freestanding ambulatory centers on an outpatient basis. If the increase in the documentation of procedures merely represented an increase in coding and not an increase in the actual execution of procedures, one would expect similar increases in the codes for acromioplasties and other outpatient orthopaedic procedures (such as knee meniscectomies, carpal tunnel releases, hallux valgus realignments, and other commonly performed outpatient procedures) since there are presumably the same phenomena of unbundling, pressures of documentation by the ABOS, and increasing financial pressures to bill for multiple codes across different types of outpatient orthopaedic procedures.
This was not the case. In Part A, there was an increase of 254.4% in the frequency of acromioplasties compared with only a 78.3% increase in other outpatient orthopaedic procedures in New York State. In Part B, there was a similar increase of 142.3% in the mean number of arthroscopic acromioplasties compared with only a 13.0% increase in the mean number of all other outpatient orthopaedic procedures reported nationally by candidates taking Part II of the orthopaedic board examination. It would be difficult to explain why there would be a preferential increase specifically in the reporting of ICD-9 procedure codes and CPT codes for acromioplasties but not other open and arthroscopic outpatient orthopaedic procedures.
Additionally, the ICD-9 procedure code (not to be confused with the ICD-9 diagnosis code) for acromioplasty—code 81.83—has not undergone modification to allow for unbundling in the way that CPT codes for shoulder surgery have been modified over the past decade; there is today, and has been for many years, a single ICD-9 procedure code for open or arthroscopic acromioplasty.
Furthermore, the codes entered in the SPARCS database each year are not ICD-9 or CPT codes reported by the physician for billing purposes, but rather they are hospital administrative data compiled by medical record coders who review physician written operative notes and produce the ICD-9 procedure codes from the medical records for transmission to the state Department of Health and insurance companies; while the operative notes are physician driven, the codes, which are then documented in the SPARCS database, are derived from independent medical coders who presumably do not have the same possible incentives that surgeons may have to report an increasing number of procedure codes.
A second reason that Dr. Schneider offers to explain the observed increase in the frequency of acromioplasties in both parts of our study is a shift in the technique of acromioplasties from open to mini-open to all-arthroscopic procedures over the last decade. The all-arthroscopic procedure was performed on an outpatient basis in recent years in contrast to open acromioplasties, which may have been performed on an inpatient basis in the earlier years of the study. Dr. Schneider speculates that, since both the SPARCS and ABOS ambulatory databases examined only procedures performed on an outpatient basis, the observed trend of increasing frequency and incidence of acromioplasty may reflect an increase in outpatient all-arthroscopic procedures but not a true increase in the number of procedures overall. While an increasing tendency to perform outpatient procedures may play some role in the overall increase in the documentation of acromioplasties observed, one would therefore expect to see an increase in the number of procedures performed at ambulatory centers over this period. This was not the case as, in the SPARCS database, there was a similarly dramatic growth in the number of procedures performed in 1996 compared with 2006 on an outpatient basis at inpatient hospitals (262.9%) compared with ambulatory surgery centers (242.5%).
While the goal of our manuscript was not to identify why there was an increase in the observed frequency and population-based incidence of acromioplasty, we speculate that this is due to a number of factors highlighted in the Discussion, which include a combination of patient-based, surgeon-based, and systems-based factors. The challenge for the future will be to further elucidate precisely why this has occurred.