We thank the reviewer for insightful comments and have responded to all
comments point-by-point.
Reviewer's report
Title: The association of underlying diagnosis with patient-reported
outcomes after revision total hip arthroplasty Version: 2 Reviewer number:
1
Referee's comments to the author(s)
Only this section of the report will be returned to the authors. Do not comment in
this section on the interest/importance level of the manuscript, or whether or not
the manuscript should be accepted.
1- The term “diagnosis” is misleading. You mean reason for revision, not diagnosis-i.e.
osteoarthritis, AVN, rheumatoid arthritis etc. This should be changed in the title and
throughout the manuscript.
Response: We have corrected this to operative diagnosis in the title and through out the
manuscript as requested.
“Operative diagnosis for revision total hip arthroplasty is associated with patientreported outcomes (PROs)”
2-It is unclear how the operative reason for revision was established. Was this based on
ICD-9 codes? If so ICD-9 codes are notoriously unreliable. Surgeon' report? You need to
have some method of validating these diagnoses. You say operative diagnosis was
obtained from the Mayo Joint Registry, but this does not adequately describe how these
variables were actually assigned to each patient.
Response: The diagnosis in the Mayo Joint registry is based on operative findings and
obtained from the surgeon’s report. We have now added this to the methods section.
“Predictor of Interest
Operative diagnosis, obtained from the surgeon’s report, was the main predictor
of interest. Based on a priori decision, diagnoses were lumped into 3 categories, as
previously [8, 22-24]: (1) loosening, wear or osteolysis; (2) dislocation, bone or
prosthesis fracture, instability or non-union; and (3) failed prior arthroplasty with
components removed or infection.”
3- In the body of the manuscript, please include p-values when comparing differences
between responders and nonrepsonders.
Response: P-values have been added, as suggested.
“Patients with higher ASA class (P<0.01), higher Deyo-Charlson index (P<0.01) and
underlying diagnosis of dislocation/fracture/instability (P<0.01) or failed prior arthroplasty
(P<0.01 and P=0.03) were less likely to respond to the survey at 2-years or 5-years,
respectively (Appendix 1).”
4- Appendix 1 in confusing, and the OR do not agree with the data presented in the text.
Is Appendix 1 a comparison within the non-responders, or between the non-responders
and responders? Do the two columns refer to 2-year and 5-year non-responders? For
example, you state” Compared to non-responders, responders at 2-years post-revision
THA were more likely to be older (age 61-70 with OR, 1.2; 71-80 with OR 1.3, compared
to #60 years)” and you reference Appendix 1. However, these data are not in the
Appendix.
Response: We regret the error in the results text, the odds ratios in the table were
correct, and the text has now been corrected. The two columns in the appendix refer to
2-year and 5-year responders, we have clarified this in the revised appendix and the
legend.
“Appendix 1. Characteristics of Survey Responders for the 2- and 5-year cohorts
compared to non-responders”
Legend:
Significant Odds ratios are in bold
*Reference category is non-responders at the respective time (2-years or 5-years)
CI, confidence interval
5- In “Data Sources” section you refer to TKA, but this is a study of THA.
Response: We regret the error and have corrected this.
“Data sources
Data on the dates of the THA, demographic details (age, gender), BMI, ASA class,
operative diagnosis, distance from the medical center and preoperative limitation in 7
ADLs…..”
6- Please reference the statement, “...however, clinical and demographic characteristics
of our study cohort were similar to other cohorts in the published studies of revision
THA..”
Response: We have added the references, as suggested.
“It remains to be seen whether our findings from single center are generalizable to other
settings; however, clinical and demographic characteristics of our study cohort were
similar to other cohorts in the published studies of revision THA [4-6].”
7- Table 1 was not formatted correctly –hard to read.
Response: We have formatted the table, as suggested
8- Your data span a large period of time, during which there were a number of secular
changes in devices being implanted, surgical and anesthetic techniques etc...which
might affect TJR outcomes. Consider including year of revision in the regression.
Response: We performed sensitivity analyses by including the year of surgery in the
multivariable model for ADL limitations at both 2- and 5-year. No significant differences
were noted in the association. This has now been added to the results.
“Sensitivity analyses were also performed adjusting for the year of surgery, since we had
included a long time period and surgical and/or anesthesia techniques may have
changed over the study time period. “
“Additional sensitivity analyses adjusting the main multivariable model for the year of
surgery did not reveal any change in interpretation or significance level for any of the
associations except that for moderate-severe ADL limitation at 2-years, the diagnosis of
components removed/infection was significant with OR of 1.7 (95% CI, 1.0, 2.9;
p=0.046), compared to borderline non-significant in the main analyses (p=0.06). The
main finding of association of dislocation/fracture/instability/non-union with significantly
higher odds (OR, 2.2; p=0.006) of moderate-severe ADL limitation at 2-years postrevision THA remained unchanged in the sensitivity analyses, with OR of 2.0 (95% CI,
1.3, 3.2; p=0.003).”
9- Similarly, did you have data on time from primary to revision surgery? This information
should be included in Table 1, and if positive in the univariate analysis be included in the
regression. Patients who have rapid failure of their primary TJR may have worse
outcomes, regardless of underlying reason for revision.
Response: We do not have data on time from primary to revision surgery, and have
included this in the limitations section.
“We lacked information regarding time from primary to revision THA, which could
potentially impact outcomes independent of the operative diagnosis.”
10- There is no reference for the STROBE statement.
Response: We have added the reference.
“We describe the methods and results as recommended in the Strengthening of
Reporting in Observational studies in Epidemiology (STROBE) statement [12].”
11-Acknowledgements: Please include the grant numbers when referencing other
support.
Response: We have added this as suggested.
“Acknowledgement: This material is the result of work supported Mayo Clinic
Orthopedic Surgery research funds and the resources and use of facilities at the
Birmingham VA Medical Center, Alabama, USA. J.A.S. is also supported by grants from
the Agency for Health Quality and Research Center for Education and Research on
Therapeutics (CERTs; U19 HS021110), National Institute of Arthritis, Musculoskeletal
and Skin Diseases (NIAMS; P50 CORT), National Institute of Aging (NIA; U01
AG18947) and National Cancer Institute (NCI; U10 CA 149950).”