Effects of Android phone vs. iPhone use on BlackBerry thumb symptoms among university students in Bangladesh

Background In Bangladesh, the most prevalent musculoskeletal condition among office employees is consid‑ ered as BlackBerry thumb (BBT). Alike official perspectives, our educational system was significantly regulating with the digital interfaces at COVID‑19 lockdown, where a greater reliance on Android phones were experienced among the adults. Numerous studies have been conducted in studying the incidences of BBT in young individuals as a result of hazards of Android phone usage (HAPU) in Bangladesh. Objective This research sought to determine the relationship between BBT symptoms and the risks associated with the using Android phones among Bangladeshi university students. Methods A nationwide cross‑sectional study was undertaken on a group of university students between the ages of 18 and 25 to determine if BBT symptoms were present based on the Finkelstein test and HAPU, which were also assessed using a well‑designed questionnaire. We calculated the crude and adjusted prevalence ratios (aPR) and used a generalized linear model from the Poisson family, using their respective 95% confidence intervals (CI). Results There were 2455 individuals in this research, with a median age of 20 and an interquartile range (IQR) of 19 to 23. Of them, 1185 males (48.27%) and 1270 women (51.75%) made up the study’s participant population. Physi‑ cal exams showed that 1300 individuals had positive Finkelstein test results (52.95%), whereas 1040 people had occasional risks from using an Android phone and 115 participants had occasional risks from using an iPhone. In our generalized linear model, we observed that participants with occasional and frequent HAPU had higher rates of BBT symptoms than responders without HAPU ( aPR = 1.73, 95% CI : 1.47–2.05, and aPR = 1.61, 95% CI : 1.29–2.00), respectively. Conclusion The current study found that Bangladeshi university students experiencing BlackBerry thumb symptoms were more likely to have risks associated with using Android phones.


Introduction
The COVID-19 outbreak and the lockdown guidelines worldwide have bought about some major challenges socially, economically, physiologically, and psychologically in people's lives.One significant lifestyle shift was the aggravated use and reliance on Android phones to access information, as an educational platform, means of communication, and entertainment [1].The posture of smartphone usage requires fixing the device with hands, looking at the device, and repetitive and consistent thumb and wrist movements [2].Prolonged duration and frequency of Android phone use with frequent movement of the upper limbs are major risk factors for musculoskeletal manifestations [3], such as BlackBerry thumb [3].Prolong or repetitive body movements are highly responsible for musculoskeletal pain [4][5][6].In this pandemic, many of one affected on musculoskeletal disorder directly or indirectly in Bangladesh [7].
BlackBerry thumb is a painful inflammatory condition involving the tendons of the abductor pollicis longus and extensor pollicis brevis in the first dorsal compartment.Although the BlackBerry thumb syndrome origin is debatable, it is attributed to myxoid degeneration with fibrous tissue deposits and increased vascularity [3].A positive Finkelstein test may be used for the diagnosis of this condition [8].BlackBerry thumb syndrome is often associated with repetitive wrist movements, specific motion requiring thumb radial abduction, and simultaneous extension and radial wrist deviation [8].Blunt trauma, biomechanical compression, overexertion from repetitive work activities, anatomical variations or abnormalities, genetic predisposition, cold temperatures, and pathogens are said to be some of the potential causes of BlackBerry thumb [8].The predicted BlackBerry thumb prevalence is 0.5% and 1.3% for men and women respectively [15], with peak prevalence among the younger generation [9].
During the COVID-19 pandemic, preventive measures such as countrywide lockdowns, social distancing, closure of educational institutes, and restrictions in movements to limit the spread of the virus have led to a drastic increase in the usage of smartphones to access information, purchase essential products, and seeking medical counseling, as a source of communication and entertainment [2], which eventually directed to rise in reliance and addiction to smartphones and devices.Many of news spared through social media which made negative impact on population for vaccination in Bangladesh [10].Studies have reported that during COVID-19, Android phone addiction increased from 26.1 to 46.7%, compared to the pre-epidemic period in children and adolescents.Moreover, the usage of Android phones multiplied to 8-12 h per day among medical students.Hazards of Android phone use were associated with an increase in daily Internet use time among university students [11].Furthermore, the time spent on social media apps such as Facebook, Twitter, and Instagram has increased, females were found to spend more time on social media and launching social media apps than males, and the use of gaming apps on Android phones has increased exponentially since the pandemic [11].
The frequent and unrestrained use of Android phones during COVID-19 is not only deleterious to psychological health but is attributable to a musculoskeletal disorder such as BlackBerry thumb [12], due to repetitive strain injuries caused by repeatedly pressing their thumbs or using a combination of thumb/finger motions.It was reported the incidence of BlackBerry thumb increased by overuse of the thumb muscle during prolonged Internet browsing, frequent texting, and gaming on Android phones [12].Several studies have reported the prevalence of BlackBerry thumb among Android phone users, and Iqbal et al. stated that more than half of the undergraduates (58.1%) using Android phones had BlackBerry thumb with the 67% of the people who used the Android phone for texting tested positive for Finkelstein's test whereas found 19.1% Android phone users tested positive for Finkelstein's test, and pain was positively correlated with the degree of smartphone use [13].Woo et al. reported that overuse of smartphones and gadgets puts excessive force on the median nerve and leads to nerve compression if repetitive movements persisted for longer periods [14].Additionally, on average, musculoskeletal complaints were usually made by people who used Android phones for more than 3 h, providing insights into how BlackBerry thumb can be a common phenomenon among Android phone users [14].
Ever since the COVID-19 pandemic, smartphone dependency has increased immensely which has become an emerging cause for BlackBerry thumb among people.Although there have been several studies that linked BlackBerry thumb with smartphone usage, there has been a dearth of studies that assessed the prevalence of BlackBerry thumb among smartphone users during COVID-19.Hence, it is imperative to conduct research that further explores the incidence of BlackBerry thumb during COVID-19 among Android phone users.The present study aimed to assess the occurrence rate and explore the risk factors of Black-Berry thumb among smartphone users during COVID-19, which will help in early diagnosis and appropriate management of BlackBerry thumb possible.

Study design
A comprehensive cross-sectional investigation was conducted on a group of university students between the ages of 18 and 25, especially those who spend around 4.15 h on average in cell phones everyday, and have been using mobile phone for at least 4 years.In the districts of Dhaka, Chattagram, Rajshahi, Khulna, Sylhet, Barishal, Mymensingh, and Rangpur, both state and private colleges were surveyed.The colleges were chosen to improve the likelihood of locating participants who fit the necessary years of age and possess cell phones.The survey was conducted between August 2022 and May 2023.

Subjects and sampling
People who used a cell phone with a minimum of two social networking platforms, like Facebook, WhatsApp, Instagram, or Twitter, were eligible to engage in the research.Participants with thumb or wrist injuries in the 3 months before the assessment, those who used a painkiller medication in the final week before the evaluation for any reason, and those working in jobs with an increased BBT danger were eliminated.Figure 1 A preliminary research study involving 50 participants yielded the data required to calculate the size of the sample.There were 36% (18/50) cases of sporadic or regular HAPU.A total of 32% (10/32) of those in the group who did not use HAPU had significant BBT signs and symptoms, compared to 45% (8/18) of those who used HAPU frequently or occasionally.An initial sample of 468 individuals would be required to identify prevalence ratios greater than 1.4 with an 80% statistically significant level of power using these values and a 95% confidence level.After adding 4% to account for the potential for incomplete responses, the total sample size, which was selected employing a non-probabilistic method of sampling, was 488 people.
In determining the sample size, Krejcie and Morgan method [15] was considered: Here, n = the sample size, N = population size, P = population portion (if unknown then 0.5), d 2 = desired margin of error (expressed as portion), and χ 2 = chi-square for specified confidence level at 1 degree of freedom [15].

Variables considered
The existence or lack of BBT symptomatology was our outcome variable, and it had two groups.The Finkelstein test, which measures the prevalence of symptoms of tenosynovitis in the extensor pollicis brevis and the abductor pollicis longus tendons, was used to analyze the result.The wrist must stay at the end of the bench on the instructor's side, while the forearm is extended and rotated in neutral during the Finkelstein test.The subject was then instructed to deviate their wrist, and the evaluator then grabbed their thumb and passively and aggressively flexed it into their hand.The Finkelstein test was carried out on both the dominant and nondominant wrists and is deemed affirmative if the subject reports Fig. 1 Diagrammatic illustration of the process used to choose the participants for the study pain to us [16].We utilized it for testing in determining the presence of BBT because the EU Handguide Group identified it as the most effective test for this reason concerning this issue [16].In a prospective cohort study with a 3-year follow-up, ultrasonographic and clinical assessments of 100 patients' positive Finkelstein test findings were contrasted.The test's sensitivity was determined to be 89% and its specificity to be 14% [17].
The observations similar to the cell phone device use survey, which asks about the use of and reliance on this technology, were used to assess the HAPU [18].Ten elements make up the test, which has a Cronbach's alpha of 0.81 and a maximum result of 40 points.Thus, we divide the participants into three groups: (a) those absent of HAPU (10 to 15 points), (b) those with infrequent HAPU (16 to 23 points), and (c) those with recurrent HAPU (from 24 to 40 points).We chose to utilize the three categories provided by the modalities for the study's objectives, so we split up the entire population into the three research groups.

Data collection
Before the data gathering, the Finkelstein maneuver instruction with a health expert was done to standardize the evaluators.Before the research started, a pilot study with 50 participants was carried out to determine the participants' general level of understanding of the topics and the study's average completion time.Then, our research team went to the colleges to invite the target audience.The proportion of participants who did not respond as well as their age, gender, and occupation was recorded to assess the possibility of selection bias.The participants orally gave their informed permission before starting their participation in the study.The first stage of the poll was then carried out using the cell phone device-the surrounding experiences questionnaire.The Finkelstein maneuver was then carried out, followed by a short discussion of protective ergonomic advice and wrist pain management tips.
To guarantee a higher poll count and prevent potential losses due to lost or erroneous data input, all the collected data was separately moved to Excel without IDs.

Statistical analysis
The statistical analysis of the quantitative variables was conducted using STATA v. 14 (StataCorp, Texas, USA).In contrast to quantitative variables, which were portrayed as medians alongside an interquartile range if they had irregular distributions or as means with standard deviation if they had symmetric distributions, qualitative variables were depicted as absolute and relative rates.One-way analysis of variance was applied when comparing number factors with uniform distributions; otherwise, the Kruskal-Wallis test was applied.To assess the qualitative variables, the chi-square test was employed.The aim of the research was evaluated using an improved linear model from the Poisson family with trustworthy standard deviations.Prevalence ratios (PR) in their raw and modified forms, along with corresponding 95% confidence intervals (CI), were given [19,20].The modified model contained the previously chosen confounding factors.After studying the scholarly literature, the following factors were determined to be confounding factors: years of age; gender; hours of usage of cell phone device per day; the number of messages delivered per day; previous week's history of inflammation due to cell phone device use; use of social networking platforms such as Instagram, Twitter, Facebook Messenger, and WhatsApp; use of digital video games; and use of the Internet.Similarly, the confounding factors' collinearity associations concerning the variables chosen to be included in the modified model were assessed.The results obtained from both the qualitative and quantitative measurements were further analyzed for verifying the statistical precision using GraphPad Prism 8.1.2[21][22][23] and R-Studio [24][25][26].In that cases, two-way ANOVA [27][28][29] and Tukey's t-test for multiple variable analysis were preferred [30][31][32].

Result
In this study, 2455 participants were included out of 2830 invited.The median age was 20 (IQR: 19-23), with 48.27% men and 51.75% women.Participants spent a median of 6 h per day on their cell phones, sending an average of 200 messages daily.The most popular platforms were WhatsApp, Facebook, and Facebook chat, with 90.63%, 90.63%, and 88.80% users respectively.Additionally, Twitter, Instagram, video games, and Internet were used by 54.18%, 64.56%, 43.58%, and 45.82% of participants.The hazards of Android phone use were assessed using the ERMUQ, resulting in a median score of 15 (range: 12-18).Half of the respondents were nonhazardous Android phone users (52.95%), while 42.36% had occasional hazards and 4.68% had frequent hazards.Physical examinations showed 52.95% positive Finkelstein test results.Additionally, 37.88% reported pain due to mobile phone use in the last week (Table 1).

Association of the study variables with hazards of Android phone use
The study included 1300 participants, with 51.54% men and 48.46% women, and a median age of 20 (IQR = 19-23).Most participants did not show hazards of Android phone use (HAPU).Among those with occasional HAPU, there were more females than males, and they spent an average of 12 h per day on their phones.Frequent HAPU was more common in females, with longer daily phone use and higher message counts.Pain due to smartphone usage was reported by a minority of participants, with higher prevalence among those with HAPU.The main online platforms used were What-sApp, Facebook, Facebook chat, Twitter, Instagram, video games, and the Internet (Table 2).The prevalence of occasional HAPU among users of various online platforms was highest for Facebook, Facebook chat, and WhatsApp, while the prevalence of frequent HAPU was highest for WhatsApp, Facebook, and Facebook chat (Table 2).

Association of the variables with the result of the Finkelstein test
The physical examination of participants showed that 52.95% had a positive Finkelstein test, with a median age of 20 (IQR = 19-22), while 47.05% had negative results, with a median age of 21 (IQR = 19-23).Those with positive results spent an average of 8 h per day on their phones and sent an average of 300 messages per day, compared to 5 h per day and 150 messages per day for those with negative results.The majority of those with positive tests reported wrist pain due to phone use, and they were more frequent users of online applications and the Internet compared to those with negative results (Table 3).

Generalized linear model crude and adjusted prevalence ratio for the association between hazards of Android phone use and the positive Finkelstein test
The participants with occasional hazards of Android phone use had a crude prevalence ratio (cPR) of 2.08 and an adjusted prevalence ratio (aPR) of 1.73, while those with frequent hazards of Android phone use had a cPR of 2.52 and an aPR of 1.61, with participants having no HAPU as the referent category.Variables related to Android phone use showed significant associations, with the number of hours using the cell  phone per day and pain due to smartphone use in the last week having notable adjusted prevalence ratios.Additionally, specific online platforms such as What-sApp and Instagram also showed significant associations (Table 4).

Discussion
This study examined the prevalence and causative factors of BlackBerry thumb among Android phone users during the COVID-19 pandemic and revealed that 52.95% tested positive for BlackBerry thumb using the Finkelstein test as a standard diagnostic test.This study's findings are similar to those of Bendezu-Quispe et al., who found that 53% of young adults who used the same diagnostic test had positive results [33].General characteristics (age, gender), variables related to Android phone use (hours using the smartphone per day, messages sent per day), frequently used social networks, hazards of Android phone use and their distribution according to variables, the Finkelstein test result distributions, the association  between hazards of Android phone use, and the positive Finkelstein test were observed among Android phone users, with a significant association found with Black-Berry thumb [33].
In our study, the majority of the participants were women (51.75%) with a median age of 20, and in another review article, Morgan et al. perceived that females mostly experienced BlackBerry thumb in the age group of 16-20 years (89%) [34].Participants spend 6 (4-10) median hours on Android phones while texting 200 (50-500) messages per day in our study, while Ali et al. found that 56% of students text more than 50 messages per day.According to Alexander et al., WhatsApp is a condition caused by excessive use of the popular instant messaging app and characterized by typical wrist pain, is a new emerging disease, and is also known as BlackBerry thumb or tenosynovitis [35].Additionally, Facebook chat, Twitter, Instagram, and the Internet were frequently used for social communications, connections, and collecting the latest information around the world during the pandemic in our study.According to Katz and Nandi, these social networking sites helped to provide formal and informal education, discussion groups, and physician and patient consultations [36].Chan et al. expressed that social media played a vital role in the dissemination of knowledge during the COVID-19 pandemic [36].Based on the Experiences Related to Mobile Phone Use Questionnaire (ERMUQ), the participants' median score was 15, and those who faced occasional and frequent Android phone usage problems were 42.36% and 4.68%, respectively.A total of 37.88% of participants complained of pain due to Android phone use in the last week; on the other hand, 42% of participants experienced thumb or wrist pain, according to Ali and his teammates [10].The prevalence of BlackBerry thumb among smartphone users of different university students in Lahore was 55%, and this study was conducted by Tahir and Ahmad [37].

Association of the study variables with hazards of Android phone use
The participants who had occasional and frequent problems with Android phone usage were mostly female, and their frequency was 53.85% and 69.57%, respectively.Long et al. revealed that the overall prevalence of hazards of Android phone use (HAPU) in their study was 21.3% among whom 53.1% were female [38].The average age of no HAPU and occasional HAPU participants was 20, while the average age of frequent HAPU participants was 19, which is significant.In our study, participants with occasional and frequent HAPU spent 7 and 12 median hours per day, while those without HAPU spent 6 median hours per day; on the other hand, 52.4% of students, who had HAPU, used more than 4 h per day in a study done by Long et al. [38].Our study revealed that frequent HAPU-experienced participants sent 700 texts per day, and among them, 60.87% experienced pain last week due to their smartphones.At the same time, occasional and no HAPU sent 178 and 200 texts per day, respectively, while 44.23% and 30.77% of them experienced pain.Sarfraz et al. discovered that 39.8% of university students had mild pain, 73 (38.2%) had moderate pain, and 4 (2.1%) had severe pain [39].WhatsApp was widely used by all HAPU groups, particularly by all frequent HAPU users.Facebook, Facebook chat, and Instagram were highly used by all categories of HAPU, and the percentage varies from 85 to 92%.Twitter, video games, and users ranged from 42 to 58% among all types of HAPU.A study conducted in Bangladesh during the COVID-19 pandemic by Hosen et al. revealed that 96.7% of participants remained online for messaging at the same time that 95.5% and 92.5% of students used Android phones for social media browsing and video watching respectively, among hazards of Android phone users [11].In another study conducted by Marengo et al., they found a positive association between hazards of Android phone usage and social networking sites like WhatsApp, Facebook, Facebook chat, and Instagram [40].

Association of the variables with the result of the Finkelstein test
Participants who showed positive test results of the Finkelstein test were 1300; among the male and female participants, 52.74% and 53.15% were positive, respectively, and the median age was 20 years.On the other hand, Ahmed et al. found that the participants' overall median age was 22.0 years [41], and among those who showed positive test results of the Finkelstein test, 66.5% were female.Participants who received a positive test result spent an average of 8 (IQR 5-12) h per day on their smartphones, sending an average of 300 (IQR 60-600) text messages, which was a very significant number.A study conducted by Ahmed et al. found that 23.7% of positive respondents spent more than 8 h per day, and 15.2% sent more than 200 test messages per day [41].The respondents to our study who tested positive and experienced pain last week were 89.25%, and this was a very significant number.Another study by Baabdullah et al. found that excessive use of smartphones and smartphone addiction lead to pain in the thumb/wrist [42].The percentage of participants who used WhatsApp, Facebook, Facebook chat, Twitter, Instagram, the Internet, and video games varies from 50 to 58%, while the percentage of participants who used negative test results varies from 39 to 50%.Shen et al. conducted a study on mobile gaming and found that it can be one of the potential risk factors for De Quervain's tenosynovitis [43].According to Bendezu-Quispe et al., higher detection of De Quervain's tenosynovitis correlated with the number of hours spent on a smartphone [33], WhatsApp usage, and experiencing pain last week due to a smartphone.

Generalized linear model crude and adjusted prevalence ratio for the association between hazards of Android phone use and the positive Finkelstein test
We used a generalized linear model to calculate a crude and adjusted prevalence ratio for different variables.In this model, we used no HAPU group as a reference to find the association between hazards of Android phone users and the positive Finkelstein test.The crude prevalence ratio (cPR) and adjusted prevalence ratio (aPR) for the occasional HAPU were 2.08 and 1.73, respectively, and the frequent HAPU were 2.52 and 1.61, respectively, and these have significant p-value.Fischer-Grote et al. found no strong evidence for age or gender as potential risk factors for developing BlackBerry thumb and HAPU [44].With a significant p-value, the number of hours spent on a cell phone per day had a cPR of 1.05 and an aPR of 1.02.The prevalence of positive Finkelstein test increased with the time spent on smartphones, as found by Reada and the team [8].The cPR and aPR for the respondents who experienced pain due to the use of the smartphone in the last week were 2.89 and 2.68, respectively, and they had a significant p-value.According to Zirek et al. [45], the prevalence of BlackBerry thumb, other musculoskeletal complaints, and pain could be increased because of extended computer and electronic gadget usage, professional demands like athletes, medical professionals, and others.In our study, the number of messages sent per day had the same cPR and aPR, which is 1.00.Different social networking sites and the Internet had different cPR and aPR, but they did not have any significant p-value in our study, while another done by Long et al. expressed that social networking, playing video games, and Internet surfing might lead to HAPU and increase the prevalence of BlackBerry thumb [38].Frequent usage of social networking media might influence the increment of hazards of Android phone usage suggested by Marino et al. [46].
This study focused on the prevalence of BlackBerry thumb among smartphone users in Bangladesh during the pandemic.This study had some limitations, as they were not able to cover all the possible risk factors due to time and resource constraints, and the participants' responses might be affected by recall bias and their psychological status.Further study is required to develop a deeper understanding of the potential risk factors and their association with BlackBerry thumb to provide awareness, education, and effective interventions.

Conclusion
The current study addresses the elevated prevalence of "BlackBerry thumb" among users of Android phones, detected through the Finkelstein test.An investigation scrutinized the hazards linked to Android phone usage, sociodemographic traits, and factors like daily phone usage duration and discomfort.The study revealed noteworthy associations between positive Finkelstein test outcomes and factors associated with Android phone usage, underscoring the necessity for a more extensive inquiry to substantiate findings and promote awareness.

Table 1
General characteristics of the sample included in the studyMedian (interquartile range).ERMUQ Experiences Related to Android Phone Use Questionnaire

Table 2
Distribution of the study variables according to hazards of Android phone useMedian (interquartile range), number (percentage).HAPU hazards of Android phone use

Table 3
Distribution of the variables according to the result of the Finkelstein test

Table 4
Generalized linear model crude and adjusted for the association between hazards of Android phone use and the positive Finkelstein test CI confidence intervals, Ref reference, PR prevalence ratio.The variable Facebook does not enter the model adjusted for being collinear with the variable WhatsApp