A novel needle for subcutaneous injection of interferon beta-1a: effect on pain in volunteers and satisfaction in patients with multiple sclerosis

Abstract

Background: To reduce injection pain and improve satisfaction, a thinner (29-gauge [29G]), sharper (5-bevel) needle than the 27G/3-bevel needle used previously to inject interferon (IFN) beta-1a, 44 or 22 mcg subcutaneously (sc) three times weekly (tiw), was developed for use in multiple sclerosis (MS).

Methods: Two clinical trials in healthy volunteers and five surveys of patients with MS were conducted to assess whether the 29G/5-bevel needle with a Thermo Plastic Elastomer (TPE) needle shield (a sleeve that houses the tip of the needle in a secure location) is an improvement over the 27G/3-bevel needle with a rubber shield for injection of IFN beta-1a, 44 or 22 mcg sc tiw. Parameters assessed were: pain and ease of insertion (healthy volunteer and nurse responses on subjective pain measurement scales); and patient satisfaction (surveys of patients with MS).

Results: In healthy volunteers, the 29G/5-bevel needle with TPE shield was associated with the least perceived pain on the Visual Analog Scale (VAS) and Verbal VAS (VB-VAS); mean VAS pain scores decreased by 40% and skin penetration improved by 69% compared with the 27G/3-bevel needle with standard rubber shield (p < 0.01). Pooled results from surveys of patients with MS indicated that 63% of patients thought that injections were less painful with the 29G/5-bevel needle than the 27G/3-bevel needle. Results from individual surveys indicated that the 29G/5-bevel needle was an improvement over the 27G/3-bevel needle for ease of insertion, injection-site reactions, bruising, burning and stinging.

Conclusion: Together these studies indicate that the 29G/5-bevel needle with the TPE shield is an improvement over the 27G/3-bevel needle with standard rubber shield in terms of pain, ease of insertion and patient satisfaction. These improvements are expected to result in improved compliance in patients with MS treated with IFN beta-1a, 44 or 22 mcg sc tiw.

Figures

Figure 1

Relationships between the Verbal Visual Analog Scale (VB-VAS) and the VAS for volunteers' perception of pain associated with injections using different needle types. The solid grey line is the fitted line and the dashed grey lines are simultaneous 95% prediction boundaries for the whole curve. The green line represents the line of perfect agreement and the estimated equation that characterizes the relationship is: VB-VAS = 4.64 + 1.12*VAS – 0.005*VAS2. TPE, Thermo Plastic Elastomer.

Figure 2

Relationships between the Verbal Visual Analog Scale (VB-VAS) and the Gracely Box SL scale for volunteers' perception of pain associated with injections using different needle types. The solid grey line is the fitted line and the dashed grey lines are simultaneous 95% predictions boundaries for the whole line. The green line represents the line of perfect agreement and the estimated equation that characterizes the relationship is: VB-VAS = 8.38 + 3.12*Gracely. TPE, Thermo Plastic Elastomer.

Figure 3

Volunteers' perception of pain associated with injections using different needle types on (a) the Visual Analog Scale (VAS) and (b) the Verbal VAS (VB-VAS) in the single-center French study (n = 120). The number next to the key indicates the magnitude of mean pain associated with each needle: 1 = lowest level of pain; 8 = highest level of pain. aNeedle currently used for the injection of interferon beta-1a (IFN β-1a), 44 or 22 mcg subcutaneously three times weekly. bSilicone lubricant B was used with this needle; for all other needles, silicone lubricant A was used. cNeedle used previously for the injection of IFN β-1a, 44 or 22 mcg sc tiw. CI, confidence interval; G, gauge; TPE, Thermo Plastic Elastomer.

Figure 4

Proportions of patients reporting that the 29-gauge (29G)/5-bevel needle was better (a 'positive' response), similar (a 'neutral' response) or worse (a 'negative' response) than the 27G/3-bevel needle for questions about pain* and skin penetration† (see Table 2 for survey questions). *Questions about pain were asked in all five surveys. †Questions about ease of skin penetration were asked in the Australian pilot survey (n = 11) and the US survey (n = 78).

Figure 5

Proportions of patients reporting that the 29-gauge (29G)/5-bevel needlea was better (responses of "much less" or "somewhat less"), similar (a "no difference" response) or worse (responses of "somewhat more" or "much more") than the 27G/3-bevel needle for questions that were unique to the US study (n = 78; see Table 2 for survey questions). aReferred to as the 'trial syringe' by the questionnaire.