There were two groups of participants included in the study, each group was used for different tests; a reliability test group and a validity test group. The participants in the study were diagnosed with RA and lived in the south of Sweden. The participants from a rehabilitation clinic were included consecutively into a smaller test group testing reliability of the MDHAQ-S. The participants from the rheumatology clinic were included consecutively in the larger test group, testing validity of the MDHAQ-S. Data were collected with questionnaires. The participants in both groups were included in the study consecutively. Written and informed consent for participating in the study was obtained from the participants. Persons who did not understand Swedish were excluded. Data of persons not willing to participate in the study were not collected. A registered physiotherapist or a registered nurse at the rehabilitation/rheumatological clinic assessed if the participant had sufficient knowledge of Swedish to be able to answer the questionnaires.
Inclusion in reliability test group
The reliability test group consisted of 30 persons with RA (diagnosed by a rheumatologist), aged > =18 yrs, registered at a rehabilitation clinic in the south of Sweden. Test-retest was to be performed by this group.
Inclusion in the validity test group
The validity test group consisted of 100 persons with RA (diagnosed by a rheumatologist), > = 18 yrs, registered at a clinic for rheumatology in the south of Sweden.
The MDHAQ-S and Arthritis Impact Measurement Scale 2– Short Form (AIMS2-SF) were used in the study. The AIMS2-SF  was used to measure the concurrent validity of the MDHAQ-S. The age of the participants was not included in the questionnaires.
The MDHAQ-S consists of the following parts: physical function, psychological status, pain, global health, fatigue, morning stiffness, and exercise habits, and includes Routine Assessment of Patient Index Data 3 (RAPID3) and Rheumatoid Arthritis Disease Activity Index (RADAI) self report joint count as well as a symptoms list and recent medical history [9, 14]. The MDHAQ-S is estimated to be performed in five minutes. The first section, “physical function”, of the MDHAQ-S (question1. a-j) includes ten activities of daily living scored 0–3 (0 = “without any difficulty”, 1 = “with some difficulty”, 2 = “with much difficulty”, and 3 = “unable to do.”). The sum of the answers is divided by three giving a score between 0 and 10. The questions concerning psychological status (question1.k-m) are scored 0 = “without any difficulty”, 1.1 = “with some difficulty”, 2.2 = “with much difficulty”, and 3.3 = “unable to do.” The sums are added to a total sum of 0–9.9. The MDHAQ-S includes visual analogue scales with 21 circles measuring pain, global health and fatigue with a total score of 0–10 in 0.5 units. The review of symptoms (question 5) is a checklist of symptoms where the checked boxes are counted. Morning stiffness (question 6) is rated by yes or no and the amount of time in minutes. Change in status (question 7) is scored: 1 = Much better, 2 = Better, 3 = Same, 4 = Worse, 5 = Much worse. Exercise frequency (question 8) is scored 3 = 3 or more times a week, 2 = 1–2 times per week, 1 = 1–2 times per month, 0 = Do not exercise regularly, 9 = Cannot exercise due to disability/ handicap. The included RADAI consists of eight joints or joint groups scored 0, 1, 2 or 3. The RADAI scores are used in the RAPID3 (0–30 scale), which include four categories: High severity >12, Moderate severity = 6.1-12, Low severity = 3.1-6, and Remission < =3. The included RAPID3 and the RADAI have high reliability . The RADAI is a valid instrument [17, 18], and patient reported tender joint count has a moderate to marked correlation to assessment by health professionals .
The MDHAQ-S also includes questions about recent medical history, which are not scored.
The AIMS2-SF is a self administered questionnaire with 26 items covering the ICF components activity limitations and participation restrictions  within five domains: physical function, symptoms, mood, social function and role function. Each item is answered using a five-point scale. Higher scores indicate higher level of impairment. The time to perform the AIMS2-SF is estimated to be ten minutes. The Arthritis Impact Measurement Scale (AIMS) was developed to assess outcome of healthcare for patients with RA  and has been further developed and shortened to the Arthritis Impact Measurement Scale 2-Short Form (AIMS2-SF) . The AIMS measures the individual´s functional, social, emotional and physical status. The AIMS-SF2 has been compared to the HAQ and been found to have better sensitivity to change than the HAQ . This makes the AIMS2-SF a relevant instrument for use for comparison with MDHAQ-S, and the instrument is relevant in terms of its contents to persons with RA . Both the HAQ and the AIMS 2 are valid and reliable instruments in Swedish [1, 22]. The AIMS has also been used to test the validity of other outcome measurement tools for patients with RA .
Translation and adaptation of the MDHAQ-S
The adaption of the MDHAQ R808  to a Swedish version (MDHAQ-S) was performed according to the guidelines by Guillemin et al. [25, 26], which include the following steps:
Translation of the MDHAQ by two independent qualified translators.
Synthesize translations, which meant to compare the translated versions in order to achieve coherence in translations. This was performed by the authors.
Back-translation by two independent back-translators.
Committee review by a multi-professional committee. The committee was a rheumatologic team consisting of a rheumatologist, physiotherapist, counselor, occupational therapist, nurse and one of the researchers.
Thirty patients testing the questionnaire with an interviewer present. The interviewer can be used as an explanatory source if needed. The interviewer observes whether there are problems reading or responding to the questionnaire and asks about the ease of completion of the questionnaire. This step is revised from the original guidelines by Guillemin and follows the protocol by Hedin et al. .
Reliability of the MDHAQ-S
Reliability was tested with test-retest with a one-week interval. The test-retest was performed at a rehabilitation clinic in a county in the south of Sweden. Reliability was also assessed with Cronbach´s alpha for internal consistency.
Validity of the MDHAQ-S
The floor and ceiling effects of the MDHAQ-S were measured in the validity test group. Floor effects were considered to be present if ≥15% scored an item as 0 (lowest possible score) and ceiling effects were considered to be present if ≥ 15% scored an item as 3 (highest possible score) on the MDHAQ-S. The content validity of the MDHAQ-S was tested by the reliability test group. The relevance of each question included was assessed with a content validity index, CVI, on a four-point scale (1- extremely relevant, 2 – quite relevant, 3 – slightly relevant and 4 – not relevant) . The scale was dichotomized by putting extremely relevant/quite relevant (1 & 2) into one group and slightly relevant/not relevant (3 & 4) into one group. This test was performed when the original HAQ was adapted to Swedish , and comparisons of the relevance of questions existing in both the HAQ and the MDHAQ-S were made. The participants were asked to add additional important questions that they felt were lacking in the instrument.
Face validity was performed within a group of professional experts as well as by the participants by their rating of the relevance of the questions of the MDHAQ-S. The group of professional experts consisted of a rheumatologist, physiotherapist, counselor, occupational therapist, nurse and one of the researchers.
Criterion validity by measuring concurrent validity was tested by asking the respondents to complete the MDHAQ-S and the AIMS2-SF and testing the results for correlation. The MDHAQ-S was tested against the Arthritis Impact Measurement Scale 2- Short Form (AIMS2-SF) for correlation. The AIMS2-SF measures the individual´s functional, social, emotional and physical status. The AIMS2-SF is a shorter and less time consuming version of the Arthritis Impact Measurement Scale −2 (AIMS2) with similar psychometric properties, convergent validity content validity, reliability and sensitivity to change [15, 21, 29]. The AIMS2-SF is easier for the patients to administer since it consists of fewer questions, 26 instead of 57. In order to achieve the best possible symptom agreement concerning arthritis pain between AIMS2 and AIMS2-SF, item 42 was replaced with item 38 in AIMS2-SF, which has been recommended in earlier studies [21, 30]. The AIMS2-SF is a relevant instrument for use for comparison with MDHAQ-S due to the instrument´s relevance of its contents to persons with RA and since the AIMS was used in the comparison with the HAQ when it was adapted to Swedish conditions . The AIMS has also been used to test the validity of other outcome measurement tools for patients with RA , and both the AIMS and the AIMS 2 are valid and reliable instruments in Swedish [1, 22].
The reliability test group: The participants answered the questionnaire twice, once at the visit to the clinic and a second time one week after the visit. The participants answered the first questionnaire at a visit to the clinic with a physiotherapist present. The questionnaires were handed out and collected by the physiotherapist at the clinic.
The validity test group: The participants answered the questionnaires at a visit to the clinic. The questionnaires were handed out and collected by the nurse at the clinic.
The reliability of the Swedish version was assessed with Cronbach´s alpha for internal consistency and test-retest for reproducibility with weighted kappa statistics and intra-class correlation. A high alpha, over 0.7, indicates that the items are adequately inter related . The test-retest measure is used to estimate the reproducibility over time when no change is estimated to have taken place. The kappa values were considered to show excellent reliability if they were >0.75, fair to good reliability for values ranging between 0.4 and 0.75 and moderate to poor agreement for values <0.4 . The floor and ceiling effects of the MDHAQ were analyzed. Content validity was tested with the content validity index (CVI). The items were considered to be relevant if the item-level CVI was >0.78 per item and the MDHAQ-S was considered to be relevant if the average of the sum of the content validity index for each item was > 0.90 [28, 33]. Concurrent validity was estimated by assessing the level of association between scores on the MDHAQ and the AIMS2-SF, with Spearman rank order correlation. Questions 5, 6 and 7 of the MDHAQ-S were not tested for correlation, since they were not considered by the authors to be relevant to be compared with AIMS2-SF. The correlations were measured comparing the total scores for each dimension of AIMS2-SF with total scores of the included dimensions of the MDHAQ-S.
The level of significance was set at p < 0.05. Data analyses were performed by SPSS 18.0 and VassarStats: website for statistical computation.
The study was approved by the regional ethics committee in Linköping (d.no: 2011/142-31).