The Projecting Subcutaneous and Self-Injectable Use Model is a web-based tool developed by Track20 to estimate the number of potential subcutaneous injectable (SC) and self-injectable (SI) users annually through 2030 for FP2020 countries.
Understanding the potential market for SC and SI users is important for family planning programs. The model presented here takes country specific information about the family planning environment to inform the growth opportunities of injectables and allows users to change key parameters to see the effects of different levels on increasing SC use. Additionally, the model allows for the separation of provider injected subcutaneous injectables and self-injectables.
The growth in subcutaneous users is theorized to come from current (intramuscular) injectable users, other short-term method users, and non-users (both from decreased discontinuation of SC and non-users who start using SC). Additional increases will come from these populations when self-injectables become fully available, because of the additional ease of use over provider administered subcutaneous injectables.
Seven parameters are user adjustable. These include:
|Proportion of Injectable users that will switch to subcutaneous||16%||Based on Burkina Faso Pilot. The share of SC user of all injectable users when methods offered in parallel at all health levels||Stout A, Wood S, Barigye G, Kaboré A, Siddo D, Ndione-Colli I. Expanding access to injectable contraception: results from pilot introduction of subcutaneous depot medroxyprogesterone acetate (DMPA-SC) in 4 African countries. Glob Health Sci Pract. 2018;6(1):55-72. https://doi.org/10.9745/GHSP-D-17-00250|
|Proportion of STM users that will switch to subcutaneous||8%||There is no available data to directly use for this parameter. The assumption is that the proportion of women switching from other STM will be less than the proportion switching from injectables. There have been studies that ask women their level of interest in switching to SI, but not a study that actually looks at the number that did switch. A 2005 survey in Ediburgh found that 67% of injectable users were interested in switching to self-injection, but only 26% of other women were (this group included some non-users as well). As a placeholder, the assumption is that this parameter is half the amount of injectables users that would switch.||Lakha, Fatim et al. The acceptability of self-administration of subcutaneous Depo-Provera. Contraception, Volume 72, Issue 1, 14 - 18. 2005. https://www.contraceptionjournal.org/article/S0010-7824(05)00014-4/fulltext|
|Proportion of Non-users who are fecund and do not want a child in the next year that will uptake to subcutaneous||1-5%||There is no available data to directly use for this parameter. The potential pool of non-users that would uptake SC are taken from the DHS. Among women not using, women who are fecund and do not want a child in the next year were considered to be potential users of SC. There is evidence that show fewer side effects of this method and more health providers able to administer is assumed to increase convenience. Khan et all predicted use of self-injectables assumed between 1 and 5% of non-users who intended to use injectables would convert to using self-injectables. Countries are given 1-5% based on their mCPR and injectables as share of the method mix. We constructed linear regressions for mCPR~InjectableShare, and the distance from the predicted line determines their new user uptake parameter. Countries with low injectable use relative to their predicted mCPR are given a higher percentage, as they are assumed to have more room to grow as SC is more like a new method than it is in places where IM injectables are already in high use.||Khan, S. , Grady, B. and Tifft, S. (2015), Estimating demand for a new contraceptive method: Projections for the introduction of Sayana Press. International Journal of Gynecology & Obstetrics, 130: E21-E24. doi:10.1016/j.ijgo.2015.03.020|
|Increase in each of the above parameters when self-injection becomes fully available (partial bonus awarded during scale up)||1-3%||Increase in each of the above parameters when self-injection becomes fully available (partial bonus awarded during scale up) 1-3% We assume that many of the benefits of SC (lower side effects, availability from lower level health care workers, increased availability due to all in one packaging) will be absorbed by the above three parameters. This parameter accounts for the ease of use of self-injection (not having to return to the health center as often). To determine a county’s default bonus, we look at the discontinuation (among all methods) because of inconvenience to use- since SI will then have more benefits of SC. We award an additional bonus for countries with high injectable use per given level of mCPR, because while they are predicted to have fewer women uptake, there will be an extra bump in SI that was not seen in SC.|
|Maximum share of subcutaneous injectables that will be self-injected||40%||We do not believe that all subcutaneous users will self-inject. First doses will generally be provider administered, and women may be comfortable receiving an injectable from a provider, but not injecting themselves. The 40% default is an estimate based on conversations with PATH’s self-injectable team.|
|Year subcutaneous is at full scale||2019-2030||Users choose the year that subcutaneous injectables are out of the pilot stage and fully available. A few countries have years provided by PATH, all other countries we set at 2022 for illustrative purposes.|
|Year self-injection reaches maximum||2019-2030||Users choose the year when self-inject reaches a maximum level. The pathway to SI availability in countries usually starts with SC. Many countries make subcutaneous injectables from providers available earlier than self-injectables. We assume a linear scale up between the year SC become available and SI is at the maximum level. A few countries have years provided by PATH, all other countries we set at 2025 for illustrative purposes.|
The model assumes increased use from decreased discontinuation, the discontinuation rates will decrease with the increased use of SC and SI because of reduced side effects and ease of access. An analysis of 3 randomized, controlled trials found a 1.26 relative risk of 12 month continuation for self-injectable versus intermuscular injectables (Kennedy CE, Yeh PT, Gaffield ML, et al. Self-administration of injectable contraception: a systematic review and meta-analysis. BMJ Global Health 2019;4:e001350. https://gh.bmj.com/content/4/2/e001350). In the model, we use country specific discontinuation rates when available for injectables and other short-term methods and reduce discontinuation by 26%. For example, if 40% of STM users discontinue within one year of use, the number of SC users who come from women who would have discontinued other methods is 0.4 times 0.26. These women come from the original "non-user category."Switching
We assume no switching from long-term methods to subcutaneous injectables.Constraining Growth
The model constrains growth based on conditions in the country prior to the introduction of subcutaneous injectables. These constraints include:
The constraints to growth are combined multiplicatively. Notes for the selected country are displayed at the bottom of the model.
The user adjusted parameters are annualized, with cumulative growth overtime.
Baseline data for the model comes from several sources:
Code for the model and shiny application can be found at https://github.com/kristinbietsch/SCSIModel
|Self-Injectable Brief for Burkina Faso||Burkina Faso|
|Self-Injectable Brief for Kenya||Kenya|
|Self-Injectable Brief for Malawi||Malawi|
|Self-Injectable Brief for Nigeria||Nigeria|
|Self-Injectable Brief for Pakistan||Pakistan|
|Self-Injectable Brief for Senegal||Senegal|
|Self-Injectable Brief for Uganda||Uganda|