Editor’s note: In the April issue of Health Affairs, Jean Mitchell reported that “self-referring” urologists, who billed Medicare for both prostate biopsies and the associated surgical pathology services, charged Medicare for more specimens per prostate biopsy than non-self-referring urologists sent to independent pathology providers. Additionally, the regression-adjusted cancer detection rate was higher for men treated by urologists who did not self-refer. “This suggests that financial incentives prompt self-referring urologists to perform prostate biopsies on men who are unlikely to have prostate cancer,” Mitchell wrote. Below, Deepak Kapoor and David Penson criticize Mitchell’s methodology and argue that it invalidates her results. Mitchell responds to this critique in a separate Health Affairs Blog post also published today. You can hear Mitchell discuss her study here.
As the physicians primarily responsible for diagnosing and treating prostate cancer, the most common malignancy among American men, urologists share the editors’ of Health Affairs desire to ensure high-quality care and appropriate utilization of health care services in this common malignancy. To this end, we appreciate the efforts of this journal in initiating a productive discussion around these issues. Unfortunately, Jean Mitchell’s article in the April Health Affairs issue is seriously methodologically flawed and factually inaccurate and, as such, does not contribute to the useful interchange of ideas needed to improve healthcare or increase value.
Prior to discussing any of the study’s numerous methodological flaws, it is critical to recognize that Doctor Mitchell is simply wrong about the standard of care with regards to prostate biopsy. The author states that it is “a common practice is to extract cores from the right and left sides of the apex, midzone, and base regions of the prostate, for six cores altogether.” In fact, the standard of care at the time of the study (2005-7) was (and still is) to obtain 10-12 cores using templates that extend the sextant pattern described above.
The clinical advantages of the 10-12 core biopsy approach were first described in the late 1990’s. By 2006, the literature was large enough to support an exhaustive systematic review by Eichler and colleagues which confirmed the superiority of the 10-12 core prostate biopsy. This review included 87 studies with the number of cores reported in individual studies ranging from 6 to 22. Schemes with 12 cores demonstrated a 31 percent improvement in cancer detection rate when compared to the standard 6-core sextant approach. This research ultimately resulted in international guidelines that specifically recommend the extended 10-12 core schema replace the six-core approach as the standard of care. (See here, here, and here.)
It is imperative for readers to understand that these consensus guidelines reflect and codify standards that were based on prevailing clinical patterns combined with previously published peer review reports; thus the guidelines follow the literature, not precede it. In fact, during the 2005-7 study period, a 10-12 core prostate biopsy was already the standard of care in the community; the “common practice” of taking only 6 cores to which Dr. Mitchell refers was below the standard at that time, as it is now. Her characterization of the overwhelming clinical evidence that led to this as “some evidence from small clinical samples from one or two institutions” is a gross misrepresentation of the scientific literature on this issue.
She goes on to assert that “there is no clinical rationale for placing each core in a separate jar.” Again, the medical evidence does not support this statement. The literature documents that submitting each of the 10-12 prostate cores to the pathologist in a single jar results in improved diagnostic accuracy. These advantages prompted one researcher to state, “Individualization of specimens in single containers is of a benefit that outweighs the costs associated with increased workload for the pathology laboratory, even if the number of biopsies is increased from sextant biopsy procedure to 10 or 12.” Both the Canadian Urological Association and The Italian Group for Developing Clinical Practice Guidelines on Performing Prostate Biopsy recommend restricting the number of cores per specimen container. (It is worth noting that these guidelines come from countries in which there is no financial incentive to send off more specimen jars, underscoring the purely clinical importance of this practice.)
Simply put, the practice of submitting one core per specimen jar is consistent with evidence-based medicine and the standard of care. Dr. Mitchell’s mistaken assertion that, rather than following the literature and providing the highest quality of care possible, practices using the single core per jar approach do so for financial gain is both fundamentally wrong and offensive.
Additional Methodological Flaws
In addition to this disregard of the medical evidence, the study suffers from a number of basic methodological flaws, any one of which invalidates interpretation of the data.
- The author indicates she used a study methodology designed to “investigate emerging market trends,” previously described in “in the peer review literature”. For these precedents, the author cites 3 studies, all written by the same author, and all published in the same non-peer reviewed industry newsletter, which is not indexed in PubMed and is not a serious scientific publication. In fact, on its website, the publication is described as “the monthly business newsletter that gets behind the headlines and press releases”.
- In addition to using a trade newsletter as a scientific source to justify her study design, she uses the same publication to choose the limited counties included in the analysis. No information was given as to how these counties were chosen a priori, nor was any statistical analysis presented to illustrate why this very small subgroup is a valid cross-section of either her study or control arms.
- The author arbitrarily elected to exclude data from hospital-based physicians. While she purported to analyze data when urologists and pathologists were in the same group, she excluded from the analysis hospital-based physicians that referred to pathologists using the same tax ID number and effectively are in the same group as well. No rationale for this decision was provided.
- Although Medicare data are available for urologists from all regions of the country, she elected to limit her analysis to selected counties, directly impacting the broader applicability of her findings and calling into question why she did this at all. She states that a larger national sample “would probably include only a small percentage of cases treated by self‐referring urologists”, yet later in the same paragraph claims that by 2011, “Approximately 2,000 urologists had established ‘in‐office’ pathology labs.” She acknowledges this as a “major limitation” of the study in the endnotes and states that she did not have the additional funds to do the more extensive analysis using the complete Medicare dataset. This is a woefully inadequate justification for what Dr. Mitchell admits is a major flaw of her study.
A Startling But Baseless Finding
The author’s most startling finding, that groups with in-house pathology labs had substantially lower diagnosis rates of prostate cancer than other groups, is based on a completely inaccurate methodology and is baseless in fact. She restricted her pool of patients eligible for prostate biopsy to only 5 diagnoses with corresponding International Classification of Disease, Ninth Edition codes (ICD-9) despite there being over 20 diagnosis codes acceptable for prostate biopsy. (Prescott-Adkins KM, vanHorn N, Hall DC. (2012). Coding Companion for Urology/Nephrology. Eden Prairie, MN: Ingenix.) She further states,
I examined the ICD-9 diagnosis codes on the corresponding professional or global claims with HCPCS code 88305 submitted to Medicare. If one or more of the claims listed diagnosis code 185, prostate cancer, or 233.4, carcinoma in situ—prostate, I constructed a dichotomous indicator to show if the beneficiary had prostate cancer.
In fact, there is no absolute requirement that the final pathological diagnosis be used for submission of the Medicare claim; the Common Procedural Terminology (CPT) indicates that CPT code 88305 (level IV – surgical pathology, gross and microscopic examination) is billable for all ICD-9 codes associated with dozens of different CPT code ranges. (Thorwarth WT, Hollman PA et al, ed. (2012) Current Procedural Terminology (CPT), Standard Edition. Chicago, IL: American Medical Association Press.) Thus, it is highly likely that groups may have billed this code with the reason for the biopsy rather than the result of the biopsy. As a consequence, it is mathematically impossible to accurately determine positive biopsy rates using this methodology.
A much more correct methodology would be to determine if any CPT code (for either evaluation and management or treatment) in the carrier file for a particular patient subsequent to the date of the prostate biopsy up to 90 days later was attached to a diagnosis of prostate cancer (185). This methodology, more costly and labor intensive but vastly more accurate, was not done for this cohort of patients. Although a more complete study is in progress, the Large Urology Group Practice Association recently conducted a preliminary review of 8 practices with in-house labs. The results indicate that with between 2 and 7 years of follow‐up, an aggregate 42,474 prostate biopsies were performed with 16,990 positives, or 40.0 percent. (See note 1 below.) We believe that her method introduced systematic bias into the analysis and that this completely invalidates the result.
As providers modify their practices to respond to the changing healthcare environment, more are adopting an integrated practice model that includes bringing services traditionally outsourced to other providers within the ordering physician’s practice. This enables the development of alternative strategies to the traditional fee-for-service model of healthcare (which may include the formation of accountable care organizations), but also creates dislocations in the market, as those providers that enjoyed historical monopolies on such services potentially find themselves losing market share. This study, funded by organizations seeking to manipulate market share by legislative fiat, used faulty methodologies and produced invalid results to demonize providers who were early adopters of evidence-based protocols. Regardless of their practice structure, these physicians were practicing evidence-based medicine that was and is consistent with the standard of care.
Note 1. Personal communication with Chesapeake Urology (Baltimore, MD); Comprehensive Urology (Dearborn, MI); Integrated Medical Professionals (Melville, NY); Michigan Institute of Urology (St. Claire Shores, MI); Orange County Urology Associates (Laguna Hills, CA); The Urology Center of Colorado (Denver, CO); The Urology Group (Cincinnati, OH); Uropartners (Chicago, IL).