In this validation study, the questionnaire was drafted ensuring content validity using relevant experts, literature review, and proper process, that is, Table of Specification. Secondly, the draft was tested for comprehensibility with two groups of target population. In this way, jargon, technical terms, ambiguous statement, double barrel items, etc. were removed to minimise measurement errors. Then the improved version was assessed using statistical analyses for reliability and validity. This validation methodology guides toward a certain degree of valid questionnaire.
The instrument has two scales: the severity of symptoms and risk level for DES and MSD. For the Internal Consistency Reliability, the Cronbach’s Alpha coefficient for symptom severity scale was 0.91 and for risk level scale was 0.88, while the Principal Component Analysis proved the discriminant and convergent validity of the questionnaire. We demonstrated that DESRIL-27 measured two scales with excellent reliability and validity on a sample of administrative staff of UBD.
While reviewing the literature on effects of digital screen use on human eye and musculoskeletal system, it was found that there is a gap in the knowledge to understand the symptoms and risk factors due to lack of validated questionnaires. Several studies used instruments which did not follow the standard patterns of questionnaire validation and due to this reason, there is discrepancy among the results, with prevalence of DES to be 19.6% in one study, and more than 80% in another study [29, 30].
When we compare our instrument to other validated questionnaires, it is found that the reliability of DESRIL-27 is superior to CVS-Q and is equivalent to CVSS17. For our instrument, the reliability coefficient (Cronbach’s alpha) for symptom severity of DES is 0.91 whereas for CVS-Q and CVSS17, it is 0.78 and 0.92 respectively. Regarding ICC (Intraclass correlation) which is done for test-retest reliability , the CVS-Q has a value of 0.80 and CVSS17 has a value of 0.85. It shows that the ICC values of both these instruments are also comparable to our reliability coefficient [15, 16].
This newly developed and validated questionnaire DESRIL-27 is unique in the sense that, in addition to eye problems, it includes items to assess the effects of musculoskeletal symptoms associated with the use of digital screens, which other questionnaires such as CVS-Q and CVSS-17 lack in [15, 16]. Hence, this questionnaire can be used as a guide for employers to create awareness on the importance of fulfilling the ergonomic requirements while at work with digital screens.
The methodology used for the questionnaire validation is considered to be the main strength of the study. All steps followed in this study were according to the standard practice of validation of health questionnaires . Both pretests and the psychometric assessment were conducted in the presence of the researchers. The questionnaire was paper based, easy to understand, with a 12-minute completion time on average.
A limitation of the study is that the diagnosis of DES is through self-reporting where reporting bias could arise. There could also be some variation in different culture and nature of workplace which could introduce measurement errors. Therefore, this questionnaire should be further evaluated in other populations and also in different work settings in future studies.
With COVID-19 pandemic continuing its presence, working or schooling from home and communication using digital technologies will inevitably be part of the new norm, where many individuals may suffer from the physical effects of overuse of digital devices. By gaining information on the symptom severity and risk levels, individuals may get away from prolonged use of digital devices. This may guide them to be more empowered in management of their health by ensuring visual and musculoskeletal health awareness. In addition, employers can explore strategies to manage DES and MSD effectively in the workplace such as adopting proper ergonomic measures, incorporating regular screen breaks and practicing the 20-20-20 rule in the workplace . Good health of workers is not only beneficial for themselves but also critical for the growth of the organizations as well as the society as a whole.
Future studies on impact of digital devices and health can include assessment of ergonomic and environmental factors. Comparative studies can also be done among different occupations in the same country and among same occupations in different countries. This will not only help determine the magnitude of DES and MSD but also the associated risk factors in other parts of the world.
The researchers have prepared a manual and a coding guideline for the scoring items to assist the researchers in conducting their future studies using DESRIL-27. All this material along with the questionnaire are available on our website (https://sites.google.com/view/thedesril-27project/).