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Physical therapists working in Saudi Arabia were invited through emails and social media to fill a web-based questionnaire. The sample size was calculated using the Raosoft calculator and based on an estimated population size of 5000 licensed physical therapists according to data posted on the World Physiotherapy website [21 ], with a confidence level of 90%, and p-value of 0.05. Accordingly, a sample of at least 257 therapists was targeted. Inclusive criteria were licensed physical therapy practitioners including physical therapists, and PT assistants working inside Saudi Arabia only. Participants gave their consent through clicking a link on the online survey.

According to statistics obtained from the MOH during the initial fieldwork, the total number of visits to specialized diabetes PHCs (n = 87) in 2020 was 944,844. The sample size was calculated using the online Raosoft^® calculator based on the assumption that the proportion of responses to most of the main questions would be 50. Using a margin of error of 5% and a confidence interval (CI) of 95%, the minimum sample size was determined to be 384. Assuming a response rate of 80%, a larger sample size of 480 was considered. Table 1 shows the total number of patients in each PHC.

The Raosoft sample size calculator was used to calculate the population size under consideration. Raosoft’s sample size calculator accepts a 5% margin of error and a 95% confidence level (Omair 2014 (link)). A total population of 100 was entered into the Raosoft calculator, yielding a sample size of 80, which was more likely to represent the population of the study. A total of 83 people took part in this study, ensuring data redundancy.

The source population of the present study comprised of registered veterinarians (Veterinary Council of India and/or State Veterinary Council) of India, and the study population included veterinarians who fulfilled the inclusion criteria of being farm animal practitioners. The sample size was calculated using the ‘Raosoft calculator’ (Raosoft: http://www.raosoft.com/samplesize.html?nosurvey). The sample size of 377 was estimated based on 50% response distribution, a 5% margin of error, and a 95% confidence interval. The expected response proportion of 50% was assumed based on the fact that both responses and response rates were completely unknown, since there are no previously published similar studies from India. Thereby, a total of 800 questionnaires were sent to the veterinarians selected through registered emails and/or personal contacts from professional societies and social media groups. The questionnaire was administrated by using the online interface of Google Forms (Google LLC, Mountain View, CA, USA) to the target population, and the survey remained open from May 2020 to June 2020.

The minimal sample size of 150 patients was calculated using the Raosoft^© calculator. As there were no prior published DRP study on TDT patients, sample size estimation was based on a local ambulatory study by Zaman Huri and Chai Ling (2013) (link) that reported a proportion of DRP of 0.9, with an absolute precision set at 0.05, confidence level of 95% and a 10% refusal rate. TDT patients were conveniently approached at the transfusion clinics between August 2021 and January 2022, screened to confirm their eligibility, and later invited to participate in the study after informed consent. Transfusion dependent thalassemia patients were defined as any thalassemia patients who required at least four regular transfusions annually (Mohd Ibrahim et al., 2020 (link)). TDT patients were enrolled if they were aged 18 years and above, had at least one clinic visit between March 2020 and April 2021 and were currently prescribed with at least one iron chelator agent. Participants with cognitive or mental incapacity or those with incomplete data, defined at 80% of missing data, were excluded from the study.

The researchers estimated the sample size using Raosoft calculator assuming a response rate of 50% and a confidence level of 95%. The estimated sample size was 380, however, the researchers decided to distribute a minimum of 1200 questionnaire to account for any un-expected scenarios of rejection to participate.