Short Form 36 (SF-36)

The SF-36 questionnaire is a globally established, validated and frequently used questionnaire that is used in various medical disciplines. It is one of the most responsive standardized status instruments used in combination with disease specific measurement tools.

Introduction

The SF-36 questionnaire (Short Form Health 36) version 1 is a further development of the Short-Form 20 score from the Medical Outcomes Study (MOS) in 1988.1-4It was modified in 1996 with regards to some item formulations and possible answers resulting in the SF-36 v2.0, the version that is in widespread use.5

Content

The SF-36 consists of 36 questions and is a general health questionnaire yielding  a profile of two health component summary measures through assessing the patient’s health status using 8 different dimensions:

  • vitality – 4 questions

  • physical functioning – 10 questions

  • bodily pain – 2 questions

  • general health perceptions – 5 questions

  • role limitations due to physical health– 4 questions

  • role limitations due to emotional health – 3 questions

  • social role functioning – 2 questions

  • mental health – 5 questions

Scoring

When evaluating the SF-36 questionnaire, it is important to consider which version of the questionnaire is used, as there are minor differences between v1.0 and v2.0 concerning the scoring.

For evaluation of the SF-36 questionnaire v1.0, all answers are first converted into predetermined points using a scoring key. The average score of all questions of the respective health dimension, e.g. physical health, is then calculated so that 8 average scores are obtained for the 8 dimensions. These describe the patient’s state of health in the respective dimensions, which can then be assessed using comparison tables.

The possible score ranges from 0 to 100 points whereby 0 points represent the greatest possible limitation of health, while 100 points represent the absence of health restrictions.6

Component analysis of the SF-36 displays two distinct concepts: a physical dimension, represented by the Physical Component Summary (PCS), and a mental dimension, represented by the Mental Component Summary (MCS) (Lins et al., 2016).7

For evaluation of SF-36 v2.0 no publicly accessible information is available currently (see license part below).

Implementation of the EQ-5D-3L

Strengths

In 2009, a systematic review showed that the SF-36 is the most widely used patient reported outcome (PRO) instrument in clinical trials. It is thus one of the most established PRO scores in medicine and its validity has already been proven in numerous studies.1,2,12-16 The SF-36 has proven to have good reliability and validity in primary care populations.9 It is also available in over 40 languages.10   Of note, the prominent PROM SF-12 was designed as a short version of the SF-36  and was validated based on assessing how well the twelve-item scale scores predicted the 36-item scale scores.11

Weaknesses

Containing 36 questions, the SF-36 is relatively lengthy compared to other general health surveys. One study showed that patients were able to answer an average of 5 questions per minute.17 Thus, it would take approximately 7 minutes to complete the SF-36 . Spending that much time answering a questionnaire is realistic in a research setting, but needs good time management, e.g. via electronic recording, to be of use in clinical practice.

License

The use of SF-36 v1.0 does not require licensing and is therefore free of charge.18 For the SF-36 v2.0 however, a license is required. The question of whether this involves costs is not discussed on the website of the rights holder.16

Conclusion

The SF-36 questionnaire is a globally established, validated and frequently used questionnaire that is used in various medical disciplines, lending it to be one of the most responsive of the standardized status instruments used in combination with disease specific measurement tools.9 It therefore has great clinical relevance and will presumably maintain its relevance in the future.