Express Scripts reported underwhelming first-quarter results on Thursday evening. While the company continues to do an enviable job at driving improved profitability per claim, overall claims volume was light and management expects that pattern to persist for the full year, prompting a $0.06 per share EPS guidance reduction.

Claims volume has been the company’s weakness in recent years, driven by a combination of post-Medco share losses and stubbornly weak per capita prescription consumption since the recession.

The first quarter’s EPS of $0.99 were flat compared with a year ago and up 8% excluding the impact of United Health (UNH $75.20)—falling a penny below our target and two cents below consensus. Better-than-expected EBITDA per claim was offset by lower claims volume compared with our model. Total claims in the quarter were 16 million below our target, while EBITDA per claim was $0.16 above expectations.

Management reduced earnings guidance for 2014 from $4.88 to $5.00 to a revised range of $4.82 to $4.94 (up 11%-14%) as a result of an expected claims shortfall of 30 million. The lower volume is being driven, surprisingly, by implementation delays for several clients as well as some in-group attrition and a slower ramp-up in new healthcare reform lives.