(Adds analyst comment, prescription volume details; updates share price)
April 29 (Reuters) - Pharmacy benefit manager Express Scripts Holding Co on Tuesday posted a lower-than-expected first-quarter profit and decreased its earnings forecast for full-year 2014, saying adjusted prescription volume would be less than it had anticipated.
Express Scripts shares fell 6 percent in extended trading.
For 2014, Express now expects adjusted earnings of $4.82 to $4.94 per share, down from its prior forecast of $4.88 to $5 per share. Analysts on average are looking for $4.94 a share.
The anticipated prescription volume shortfall that led to the decision to revise the 2014 forecast downward was primarily due to a delay of expected client starts from the middle of the year to early 2015, and to lost clients, Express Scripts said.
The shortfall would be partially offset by an increase in earnings per adjusted claim, the company said.
Excluding one-time items, Express said it had adjusted earnings of 99 cents per share, missing analysts' average forecast by 2 cents, according to Thomson Reuters I/B/E/S.
The company said severe winter weather in the quarter as well as later-than-expected enrollment in public health insurance exchanges under the Affordable Care Act hurt its results.
"They had a pretty challenging start to the year," said ISI Group analyst Ross Muken.
He said the original prescription volume forecast had seemed conservative at the time, "and now it's not."
Express now expects adjusted prescription volume to be in the range of 1.27 billion to 1.33 billion, down from its previous forecast of 1.30 billion to 1.36 billion.
"If you have less scripts, you're going to make less money," Muken said. "On the whole, we're pretty concerned."
Pharmacy benefit managers, or PBMs, administer drug benefits for employers and health plans and also run large mail order pharmacies.
Chief Executive George Paz said the company expects to substantially complete integration of its 2012 acquisition of rival Medco through the remainder of the year and then to turn its attention to growth.
The company said net profit fell to $328.3 million, or 42 cents per share, from $373 million, or 45 cents per share, a year ago.
Revenue of $23.68 billion was shy of Wall Street estimates of $23.80 billion.
Express Scripts shares fell to $66.75 in after-hours trading on Nasdaq after closing on Tuesday at $71.01.
(Reporting by Bill Berkrot; editing by G Crosse, David Gregorio and Meredith Mazzilli)