Survey Design
A 20-item survey was designed to measure the amount of time spent using smartphones per day, classify the type of phone used, and quantify skin changes noticed by each respondent. Demographic information for each respondent also was gathered using the survey. The survey was pilot tested to ensure that respondents were able to understand the items.
One item asked if respondents owned a handheld smartphone. Two items assessed how much time was spent on smartphones per day (ie, <1 hour, 1–2 hours, 2–3 hours, 3–4 hours, 4–5 hours, >5 hours) and the type of smartphone used (ie, Apple iPhone, Samsung Galaxy, Google Pixel, Huawei, LG, other). Six items assessed skin changes to the digits, namely the fifth digit (eg, Do you notice any changes to your fifth digit [pinky finger] that would likely be contributed to how you hold your smartphone, such as divot, callus, bruise, wound, misalignment, bend?). Eleven items were used to collect basic demographic information, including age, sex, legal marital status, ethnicity, race, annual household income, highest-earned educational degree, current employment status, health insurance status, and state of residence.
Statistical Analysis
All data were analyzed using IBM SPSS Statistics 23. The association between changes to the fifth digit and time spent on the phone, hand dominance, and socioeconomic factors (ie, age, sex, legal marital status, ethnicity, race, highest-earned educational degree, current employment status, health insurance status, annual household income, state of residence) was analyzed using logistic regression, with changes to the fifth digit as the dependent variable and time spent on the phone, dominant hand, and socioeconomic factors as independent variables. Measures of central tendency, frequencies, and other descriptive analyses were used to define the characteristics of the sample. The bivariate associations between changes to the fifth digit and time spent on the phone, hand dominance, and socioeconomic factors were examined using χ2 analysis, correlational analysis, and t tests. Statistical significance was set at P≤.05.
Results
The mean age of the 374 respondents was 33.8 years (range, 18–72 years). One hundred nine respondents were men (29.1%), 262 were women (70.1%), and 3 did not specify (0.8%). Two hundred thirty-four respondents (62.6%) were single, 271 (72.5%) were white, 171 (45.7%) had a bachelor’s degree, and174 (46.5%) were employed full time. Annual household income was normally distributed among the respondents, with 28 (7.5%) earning less than $10,000 per year, 130 (34.8%) earning $10,000 to$49,999 per year, 136 (36.4%) earning $50,000 to $99,999 per year, 52 (13.9%) earning $100,000 to$149,999 per year, and 28 (7.5%) earning more than $150,000 per year. The demographic characteristics of the respondents are presented in Table 1.
Eighty-five (22.7%) respondents admitted to changes to the fifth digit that they associated with holding a smartphone, whereas 289 (77.3%) reported no changes. When asked about the average amount of time spent on their smartphone per day, 17 (4.5%) respondents answered less than 1 hour, 70 (18.7%) answered 1 to 2 hours, 69 (18.4%) answered 2 to 3 hours, 77 (20.6%) answered 3 to 4 hours, 57 (15.2%) answered 4 to 5 hours, and 84 (22.5%) answered more than 5 hours. One hundred ninety-nine (53.2%) respondents indicated they used an Apple iPhone, 95 (25.4%) used a Samsung Galaxy phone, 9 (2.4%) used a Google Pixel phone, 3 (0.8%) used a Huawei phone, 23 (6.1%) used an LG phone, and 45 (12.0%) used another type of smartphone. The characteristics of smartphone use as reported by the respondents are presented in Table 2.
