Persistent Pain After Hip Replacement
Condition: Persistent Postsurgical Pain; Arthritis Hip; Neuropathic Pain; Opioid Use
MeSH terms: Neuralgia; Pain, Postoperative
Study type: Observational

Summary: 
      This study is a nationwide cross-sectional survey on pain and satisfaction after total hip
      arthroplasty (THA). Please find the full protocol uploaded on ClinicalTrials.gov
    

Detailed description: 
      The study is registered at the Capitol region of Denmark's regional research listing
      (Pactius) with identifier P-2022-933, approved 23 December 2022. The resulting paper will be
      reported according to the CROSS checklist for standardised reporting of survey studies.
      Wherever needed, a trained linguist translated questions from English to Danish and vice
      versa. The Danish and an English version of the questionnaire will be available in the final
      publication.

        -  Study design: This study is a nationwide cross-sectional survey.

        -  Patient involvement: A panel of patients helped develop the questionnaire, i.e. testing
           and selecting the questions.

        -  Questionnaire: The questionnaire is composed of 22 questions (please see the uploaded
           protocol), however patients answering "No" to question 3 skips questions 4-17 concerning
           pain in the operated hip. Only question 3, 4, 20, and 21 are mandatory as to avoid
           non-respondents. The full questionnaire translated to English can be found in the
           supplementary material in the protocol. Contact information for the first author (JL) is
           supplied in the contact letter in case the patients have difficulties with filling in
           the questionnaire, have questions, or believe they have been selected mistakenly.
           Similar or identical questions to those in a survey published in 2006 to increase the
           ability to compare results (i.e., questions 3-5, 8, 10 and 13)

        -  Sample characteristics: Eligible patients are all adult (18 years or older) patients
           operated with primary THA for osteoarthritis between 1 March and May 31, 2022. Legally
           incompetent citizens, i.e., persons with a legal guardian, will not be asked to
           participate. Patients will be identified from the Danish National Patient Register
           through the Danish Health Data Authority (SKS-code DM16 [hip osteoarthritis] + KNFB
           [Primary Total Hip Arthroplasty]). Baseline data of respondents and non-respondents are
           gathered from the Danish Hip Arthroplasty Register. To evaluate the generalisability of
           the study, respondents' baseline data will be compared to the non-respondents baseline
           data in the paper's Table 1.

        -  Sample size calculation: With an estimated 12% incidence of the primary outcome
           (patients with moderate or severe pain at rest and/or while walking) and a 70% response
           rate, 2577 patients are needed to yield a 95% confidence interval of 3 percentage points
           (10.5-13.5). This level of certainty is appropriate because differences less than this,
           may be hard to interpret by clinicians and patients. Sampling patients that were
           operated during 3 months outside holiday season should yield approximately this number
           of identified patients.

        -  Ethical considerations: This study was approved by the local institutional review board
           and contact information are provided by the Danish Health Data Authority. Telephone
           numbers for non-respondents are found by searching the CPR number in the electronic
           patient files, but without accessing the patients' health data. According to Danish
           legislation, approval from the national ethics committee is neither required nor
           possible to obtain for survey studies (see attached 'exempt from notification' letter
           from the Danish national ethics committee).
    

Intervention name(s): Primary Total Hip Arthroplasty
Intervention type(s): Procedure
Intervention description(s): All patients surveyed have undergone primary total hip arthroplasty approximately 1 year prior to survey distribution
Other intervention name(s): Primary Total Hip Replacement
Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Patients are identifed from the Danish National Patient Register through the Danish Health
        Data Authority (SKS-code DM16 [hip osteoarthritis] + KNFB [Primary Total Hip
        Arthroplasty]). Baseline data of respondents and non-respondents are gathered from the
        Danish Hip Arthroplasty Register.