On the hospital floor or in the doctor’s office, validation of efforts in healthcare can sometimes be more obvious and immediate — but for many of those in pharma, from R&D to launch teams, the gap between potential and real-world outcome is widened by repeated patient drop-off. And it can grind the initial hope and enthusiasm for long-term patient impact down to the thinness of a playing card.
So what’s causing the gap between the successful launch of a new pharmaceutical and the outcomes in practice?
It’s what the pharma industry refers to as the “leaky bucket,” and it reveals a failure in the supporting structures to intervene at critical moments. The bucket represents the total eligible patient population, and every hole in the bucket is a point in the journey where patients leak out — from never starting therapy to not dosing accurately or consistently, or discontinuing completely. The water that remains is the persistently treated patient population, who are the only ones actually experiencing the full clinical benefit of the drug.
Pharma and life sciences companies work hard to fill the bucket with new patients through physician engagement and acquisition efforts that include patient education, onboarding guidance, co-pay assistance and financial support, and prior authorization. Yet this tremendous effort to get patients started on therapy is countered by an almost equally powerful force that drains them away: lack of persistence and adherence.
And these don’t just reduce the return on large R&D investments; they also harm patients who need continuous therapy to stay well.
While pharma often measures success by starts and first fills, fewer than half of novel prescriptions written are ever filled. And of those patients who do start therapy in the U.S., only 29% are still on it at the end of 12 months.1 In fact, adherence and persistence challenges affect every brand, indication, and delivery mechanism — creating both a devastating toll on human health and an annual loss of more than $600 billion.2 Pharma revenue from chronic therapies accrues over time, so persistence timing directly determines captured lifetime value.
The real value, then, must come from how long patients stay on therapy by plugging the holes in the journey.
Persistence represents the time (days, months, or years) over which a patient continues a prescribed treatment and tracks whether they stay on therapy. It's distinct from adherence, which measures whether a patient takes the right dose at the right time.
There is something fundamentally wrong when a breakthrough in science can’t gain the momentum it needs to reach long-term effectiveness. When patients stop therapy early, they may lose symptom control, face disease progression, or end up needing more complex and costly care later.
This persistence problem isn’t a flaw of the science or the go-to-market plan, nor of the physicians or the activated patients. It’s a flaw in a system that wasn’t designed to provide seamless long-term patient support. Yet, while it’s one of the most important problems to solve, there’s no one solution for how to keep patients on therapy.
The reason? After activation, the patient’s brand team is left in the dark about what happens next — and that's where things can go sideways. At a time when a well-honed intervention is needed most, there are no real-time signals, early warnings, or way to see a patient drifting before they're already gone.
The best solution is one that combines deep personalization with pharmaceutical expertise to drive long-term value and solve for post-activation persistence. While increases in days on therapy were limited across most therapy areas in 2024, immunology medicine use grew 11% as more patients across a broader range of autoimmune and inflammatory diseases gained access to novel medicines to treat these chronic, often-debilitating conditions.3 This is a tremendous opportunity for filling the bucket, but can pharma companies retain these gains?
Plugging the leaky bucket is imperative. It positively impacts everyone from the dedicated researchers who developed the molecule to the patients who experience improved quality of life by staying on the treatment long enough to see its full benefits. For pharma companies specifically, persistence matters because it protects both outcomes and revenue. And for patients, improved persistence means they are more likely to benefit from the drug long enough to matter clinically, which is especially important for chronic therapies and specialty medicines.
1 Shaw, Gina. "Half of Novel Specialty Prescriptions Go Unfilled, IQVIA Data Show." Specialty Pharmacy Continuum, April 10, 2026
2 HealthPrize Technologies and Capgemini. Pharmaceutical Companies Lose $637 Billion in Revenue Annually Due to Medication Nonadherence (Estimated Annual Global Pharmaceutical Revenue Loss Report Update). Norwalk, Conn.: PRNewswire; November 16, 2016
3 IQVIA Institute for Human Data Science. Understanding the Use of Medicines in the U.S. 2025: Evolving Standards of Care, Patient Access, and Spending. April 2025.