Analgesia for pain during subcutaneous injection: effectiveness of manual pressure application before injection.

Background: It is necessary to establish an effective subcutaneous injection procedure for adult and elderly individuals because many drugs such as hormones and interferon are generally delivered by subcutaneous injection. We tested whether pain during subcutaneous injection can be decreased by prior application of localized manual pressure at the injection site.

Methods: In this semirandomized, open-label study evaluating the manual pressure method for transient analgesia, physicians applied pressure with their thumbs for 10 seconds to create a nonpainful skin depression at the injection site immediately before subcutaneous injection of the influenza vaccine to patients. Control patients received the vaccine by the same route, but without prior application of focal pressure. In addition to pain, we evaluated patient age, gender, height, weight, body mass index, body temperature, and fat thickness at the brachial triceps muscle. Pain intensity was estimated using a 100 mm visual analog scale (VAS) and the face scale (FS). Categorical variables were compared using Chi-square tests and continuous variables were compared using unpaired t-tests between the intervention group and control group. Multivariate analysis was performed using the VAS or FS score as the dependent variable and weight, age, height, fat thickness at the brachial triceps muscle, and body temperature as independent variables.

Results: There were no significant differences in demographic variables, VAS scores (22.5 ± 23.0 versus 21.2 ± 23.6, P = 0.4), or FS scores (2.5 ± 2.1 versus 2.4 ± 2.1, P = 0.4) between the intervention and control groups. There was a significant negative correlation between age and subjective pain intensity (VAS, r = -0.32; FS, r = -0.28).

Conclusion: The manual pressure method was not effective in decreasing pain during subcutaneous injection. Alternative methods of focal transient analgesia should be developed to improve vaccination rates and relieve anxiety associated with subcutaneous injection.