What variables should inform needle length choice for deltoid intramuscular injection? A systematic review

OBJECTIVES

(1) Assess the distribution of skin-to-deltoid-muscle distance (SDMD) at the deltoid intramuscular (IM) injection site; (2) its relationship with demographic and anthropometric variables and (3) Consider the findings in relation to clinical guidance on IM injection, such as COVID-19 vaccines.

DESIGN

Systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA SOURCES

MEDLINE, EMBASE, ClinicalTrials.gov, Cochrane Library, CINAHL and SCOPUS between June and July 2021 with no publication date limit.

ELIGIBILITY CRITERIA

Studies reporting measurements of the SDMD in living adults aged 16 years and older, at the deltoid IM injection site, published in English were considered.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers performed each stage of screening, data extraction and quality assessments using the Joanna Briggs Institute Critical Appraisal Checklist for analytical cross sectional studies.

RESULTS

16 105 papers were identified, of which 11 studies were suitable for review, representing 1414 participants. Heterogeneity in the definition of the deltoid IM injection site, locations measured and methods of measurement precluded meta-analysis. Evidence from ultrasound SDMD measurements demonstrated some patients in all but 'underweight' body mass index (BMI) categories, may require needles longer than 25 mm for successful IM injection. Calliper measurements overestimated SDMD compared with ultrasound. Female sex, higher BMI categories and greater weight in women were associated with greater SDMD.

CONCLUSIONS

The reviewed evidence was insufficient to inform definitive needle length 'cut points' for IM injection based on demographic or anthropomorphic variables. Contemporary clinical guidance currently based on this evidence, including the site of injection and choice of needle length, may result in subcutaneous administration in a small proportion of recipients, particularly if obese or of female sex.

PROSPERO REGISTRATION NUMBER

CRD42021264625.

Revisiting trajectories of BMI in youth: An in-depth analysis of differences between BMI and other adiposity measures

OBJECTIVE

Body mass index (BMI) is used to identify trajectories of adiposity in youth, but it does not distinguish fat- from fat-free-mass. There are other inexpensive measures of adiposity which might better capture fat-mass in youth The objective of this study is to examine differences between sex-specific trajectories of BMI and other adiposity indicators (subscapular and triceps skinfold thickness, waist circumference, waist-to-height ratio) which may better capture fat-mass in youth.

METHODS

Data come from four cycles of a longitudinal cohort of 1293 students in Montréal, Canada at ages 12, 15, 17 and 24. Group-based trajectory models identified sex-specific adiposity trajectories among participants with data in ≥3 cycles (n = 417 males; n = 445 females).

RESULTS

There were six trajectory groups in males and females for all five indicators, except for waist circumference (seven) in both sexes and triceps skinfold thickness (four) and waist-to-height ratio (five) in females. Most trajectories indicated linear increases; only the skinfold thickness indicators identified a decreasing trajectory. While all indicators identified a trajectory with high levels of adiposity, they differed in the number and relative size of trajectories pertaining to individuals in lower half of the adiposity distribution.

CONCLUSION

BMI is a satisfactory indicator of adiposity in youth if the aim of the trajectory analysis is to identify youth with excess adiposity, a known risk factor for cardiometabolic outcomes in adulthood.