A patient care program for adjusting the autoinjector needle depth according to subcutaneous tissue thickness in patients with multiple sclerosis receiving subcutaneous injections of glatiramer acetate

Abstract

Background: The perceived pain on injection site caused by subcutaneous (SC) self-injection may negatively affect acceptance and adherence to treatment in patients with multiple sclerosis (MS). Pain on injection may be caused by inaccurate injection technique, inadequate needle length adjustment, or repeated use of the same injection body area. However, information is lacking concerning the optimal needle depth to minimize the injection pain.

Objective: The purpose of this program was to characterize the perceived injection-site pain associated with the use of various injection depths of the autoinjector of glatiramer acetate (GA) based on SC tissue thickness (SCT) of the injection site.

Methods: This was a pilot program performed by MS-specialized nurses in patients with MS new to GA. Patients were trained by MS nurses on the preparation and administration of SC injection and on an eight-site rotation (left and right arms, thighs, abdomen, and upper quadrant of the buttock). The needle length setting was selected based on SCT measures as follows: 4 or 6 mm for SCT < 25 mm, 6 or 8 mm for SCT between 25 and 50 mm, and 8 or 10 mm for SCT > 50 mm. Injection pain was rated using a visual analog scale (VAS) at 5- and 40-minute postinjection and during two 24-day treatment periods.

Results: Thirty-eight patients with MS were evaluated. The mean SCT ranged from 15.5 mm in the upper outer quadrant of the buttocks to 29.2 mm in the thighs. The mean perceived pain on injection was below 3 for all the injection sites, at both time points (5 and 40 minutes) and during both 24-day evaluation periods. The mean VAS scores were significantly greater after 5 minutes of injection compared with that reported 40-minute postinjection during both 24-day treatment periods and for all the injection areas. Mean VAS measures at 5- and 40-minute postinjection significantly decreased during the second 24-day treatment period with respect to that reported during the first 24 SC injections for all injection sites.

Conclusions: Our findings suggest that the adjustment of injection depth of SC GA autoinjector according to SCT of body injection areas is suitable to maintain a low degree of postinjection pain. Moreover, our results also may indicate that the use of needle lengths of 6 mm or shorter is appropriate with regard to injection pain for adult patients with MS with SCT < 50 mm.

FIGURE 1

Median Pain (and Standard Error), Assessed by VAS, at 5 and 40 Minutes Postinjection During the First (A) and Second (B) 24-Day Treatment Periods in the Dominant and Nondominant Sides of the Injection Body Areas (Arm, Thigh, Abdomen, and Upper Quadrant of the Buttock)

FIGURE 2

Median VAS Scores (and Standard Error) During the First and Second 24-Day Treatment Periods at 5 and 40 Minutes Postinjection in the Arm, Thigh, Abdomen, and Upper Quadrant of the Buttock

FIGURE 3

Mean VAS Scores (and Standard Error) Reported with the 4-, 6-, and 8-mm Needles at 5 and 40 Minutes Postinjection and During the First and Second Treatment Periods (Visits 1 and 2) in the Arm (A), Thigh (B), Abdomen (C), and Upper Quadrant of the Buttock (D) Note. There was only 1 patient who used the 10-mm needle in the study because of a SCT > 50 mm in the thigh (B). In addition, D shows the VAS scores for the 4- and 6-mm needle given that only 3 patients at visit 1 and 2 patients at visit 2 used the 8-mm needle in the upper quadrant of the buttock and data would not be comparable. (B) There were 35 evaluable patients for pain at the thigh: 33 patients applied injections according to the needle depth adjustment protocol in both thighs, and 2 patients used the suitable depth in only one thigh (6- and 8-mm needle, respectively). (C) There were 37 evaluable patients for pain at the abdomen: 33 patients applied the recommended needle depth in both sides of the abdomen, and 4 patients used the adequate needle depth in only one side (3 patients: 6-mm needle; 1 patient: 8-mm needle). (D) There were 33 evaluable patients for pain at the upper quadrant of the buttock: 29 patients used the recommended needle depth for both sides, and 4 patients applied the adequate needle depth in only one side (6-mm needle).