The Musculoskeletal Tumor Society Scoring system is a valid subjective and objective tool to evaluate outcomes of surgical treatment of patients affected by upper and lower extremity tumors

Treatments of oncological diseases of musculoskeletal system mostly aim to guarantee function and quality of life (QoL) at their best, especially when eradication of the neoplasia is not achievable. Although in the past most outcome studies focused on survival rate and local recurrences as primary outcomes, in the last decades more emphasis has been placed on patient’s perspective. It has been shown that taking into account patient perception promotes communication, improves decision-making process and increases patient satisfaction. Objective measures integrated with patient perception could provide better medical care [1‐3].

The Musculoskeletal Tumor Society (MSTS) score was developed in 1993 as an objective tool to measure functional outcome in patients affected by neoplasms [4]. Even if the MSTS score has been never properly validated in its original version [4], it is widely used in clinical practice. As a matter of fact, the original version underwent cross-cultural adaptation and validation in several languages, such as Greek [5], Danish [6], Brazilian [7], Chinese [8], Japanese [9], French [10] and Turkish [11].

The score is available for upper and lower limb [12]. Main strengths of the score mainly rely on ease of use and briefness [13]. Main concern is that the MSTS score was formulated as an objective tool (hetero-administered), but it is currently worldwide used as a patient-reported outcome measure (PROM) (self-administered).

The main purpose of the present study is to evaluate if there is a difference between objective or subjective administration of the MSTS score in a cohort of patients affected by musculoskeletal oncological diseases. The hypothesis of the study is that there are no differences between patient- and clinician-reported outcomes using the MSTS score for both lower and upper limb.

No major issues were encountered during translation from the original version. No major difficulties in comprehension were revealed during testing the pre-final version. Patients took about 5–10 min to complete the questionnaire (see Appendix 1).

The psychometric properties were tested on a finale sample of 110 patients: 59 affected by lower extremity involvement and 51 affected by upper extremity involvement. Patients’ characteristics are shown in Tables 1 and 2, for upper and lower limb, respectively.

Main finding of the present study was that MSTS score can be interchangeably used as a PROM or as an objective tool because both administration modalities showed to be valid and the correlation between the two was very high. At the same time, it must be highlighted that the Italian version of the MSTS score showed good psychometric properties for both lower and upper extremity.

MSTS score has been originally developed as a clinician-administered questionnaire and it is now widely used to evaluate residual function in patients with extremity tumors [4]. However, even if it has been developed to be completed by an examiner, MSTS score is often reported in the literature as a self-administered tool [22] or even as a mixed version with some questions completed by the patient and some others completed by the clinician.

Marchese et al. [23] and Ginsberg et al. [24] assessed functional outcomes in patients affected by lower extremity sarcomas. Both studies used the MSTS score by asking patients to complete pain, emotional acceptance and supports, while physical therapists rated gait and walking abilities.

Janssen et al. [25] first compared self- and hetero-administered modality of the original version, in a study about functional outcome after surgery in patients affected by lower and upper extremity bone metastasis. According to the authors, clinician reports overestimate function as compared to the patient perceived score. This assumption strongly differs from the outcome of the present study. The reason probably relies in the study design. As recognized by the authors [25], they collected the clinician reports by resuming information from previously noted medical records, but the score was developed to be completed at the time of consultation. As a matter of fact, the discrepancy was the largest for the common overall function and emotional acceptance domains. In the present study, patients were directly visited and interviewed by the clinician, who filled out the form during the clinical examination, thus reducing the risk of possible misinterpretations.

Looking at the results of the psychometric properties, some issues deserve further explanation.

The original version of MSTS score was never properly validated, therefore results of the present study can be only compared to other cross-cultural adaptations [5‐11, 26]. We observed that ceiling effect was high for all questions both for upper and lower extremity forms, which it means that the questionnaire cannot distinguish higher functioning patients. This finding is in agreement with previous studies [6, 7, 26, 27]. At least two possible explanations can be attempted. First, MSTS score was developed in a time when limb savage surgery and reconstructive options were less common, and expectations on functional results were quite low. Secondly, a sensitivity analysis aiming to distinguish between hystotypes or at least between aggressive, intermediate and benign tumors could have probably lowered or partially better explained the effect. Saebye et al. [6], in their study on cross-cultural adaptation and validation of Danish version of MSTS score, found no ceiling effect among patients with lower extremity bone sarcomas or high aggressive tumors after stratification. Rebolledo et al. [7] provided cross-cultural adaptation and validation of the Brazilian Portuguese MSTS score. They only included patients who underwent limb salvage surgery or amputation for primary sarcoma of the lower limb, and no ceiling effect was reported. Unfortunately, sample size of the present study did not allow stratification for hystotype, albeit a strong and valid outcome measurement tool should be as universal as possible. Inclusion criteria of the present study were kept wide on purpose. In fact, MSTS score is widely used for any kind of tumor, and therefore, it was deemed important to be as inclusive as possible.

In agreement with previous translations of MSTS questionnaire [5, 7‐9, 26], we observed that the instrument composed by all six items is able to evaluate one latent factor (e.g., lower or upper limb function).

TESS and SF-36 were chosen to test the construct validity to be consistent with the previously translated versions [5, 7‐9, 11, 26]. MSTS and TESS reported moderate to strong correlation in all studies. Results differed and became controversial when it comes to SF-36. While some studies [9, 11, 26, 27] showed better correlation with the physical component of SF-36, some others did not [5]. However, the SF-36 is a tool designed and widely used as a general health and health-related QoL assessment measurement, thus this controversial correlation can be easily understood.

In terms of reliability, we found a Cronbach’s alpha coefficient > 0.95 for both upper and lower extremity in each administration modality. A general accepted rule is that Cronbach’s alpha of 0.6–0.7 indicates an acceptable level of reliability, and 0.8 or greater a very good level. However, values higher than 0.95 are not necessarily good, since they might be an indication of redundance [28]. Overall, previous cross-cultural adaptations of MSTS score showed a Cronbach’s alpha between 0.70 and 0.90. Once again, the different values of Cronbach’s alpha in the present study are possibly due to indirect influence from external factors such as heterogeneity of study population [20].

The present study has some limitations. First, as already mentioned, a sensitivity analysis could have been clarified some controversial psychometric properties. However, it must be highlighted that results are comparable to other cross-cultural adaptations of the questionnaire. Therefore, the major flaw is probably that the original version has never been properly tested. At the same time, as the MSTS score is the most popular and widely used, it was mandatory to provide an Italian version. The added value of the study relies on its main purpose: the comparison between self- and hetero-administration of the score. Second, only patients attending the outpatient clinic were asked to participate in the study. It must be considered that somehow patients with progressive disease or unsatisfied patients are less likely to be available for testing in the same setting.

In conclusion, the Italian version of the MSTS is a valid tool to evaluate outcomes of surgical treatment of patients affected by extremities tumors and it can be used as a subjective tool for both lower and upper extremity.