Alexion Pharmaceuticals, Inc. ALXN is scheduled to report first-quarter 2016 earnings results on Apr 28, before the opening bell.Alexion’s track record has been disappointing so far. Over the four trailing quarters, the company has posted an average negative earnings surprise of 2.10%, having beaten estimates in only one quarter and missing in the rest.Let’s see how things are shaping up for this quarter.Factors at PlaySoliris, the main growth driver at Alexion, is expected to keep up its performance in the approved indications paroxysmal nocturnal hemoglobinuria, and atypical hemolytic uremic syndrome thereby driving top-line growth. The company continues to add new patients in both the indications.The launch Kanuma and Strensiq should also contribute to revenues and reduce the company’s dependence on a single product for growth.Strensiq’s launch, however, is projected to be sluggish as is the case with therapies for ultra-rare diseases, mainly due to low incidents, high mortality among hypophosphatasia patients, and low awareness of the disease.In its fourth-quarter call, the company provided its guidance for the first quarter of 2016. Revenues are expected in the range of $735 million to $745 million in constant currency, excluding the impact of $35 million due to foreign exchange headwinds. The company projects earnings in the range of $1.10–$1.15 per share.What Our Model IndicatesOur proven model does not conclusively show that Alexion is likely to beat on earnings this quarter. That is because a stock needs to have both a positive Earnings ESP and a Zacks Rank #1 (Strong Buy), #2 (Buy) or #3 (Hold) to likely post an earnings beat. But that is not the case here, as you will see below.Zacks ESP: The Earnings ESP, which represents the difference between the Most Accurate Estimate and the Zacks Consensus Estimate, is 0.00%. This is because both the Most Accurate Estimate and the Zacks Consensus Estimate stand at 91 cents.Zacks Rank: Although the company’s Zacks Rank #3 enhances the predictive power of the ESP, its 0.00% ESP makes surprise prediction difficult.Note that we caution against stocks with a Zacks Rank #4 or #5 (Sell-rated stocks) going into the earnings announcement, especially when the company is seeing negative estimate revisions.Stocks That Warrant a LookHere are a few health care stocks that you may want to consider, as our model shows that they have the right combination of elements to post an earnings beat this quarter.Innoviva, Inc. INVA has an Earnings ESP of +77.78% and a Zacks Rank #2. It is scheduled to report first-quarter results on Apr 28.The Earnings ESP for BioMarin Pharmaceutical Inc. BMRN is +22.35% and it carries a Zacks Rank #3. The company is scheduled to release first-quarter results on Apr 28.The Earnings ESP for Sanofi SNY is +4.17% and it carries a Zacks Rank #2. The company is scheduled to release first-quarter results on Apr 29.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report SANOFI-AVENTIS (SNY): Free Stock Analysis Report ALEXION PHARMA (ALXN): Free Stock Analysis Report BIOMARIN PHARMA (BMRN): Free Stock Analysis Report INNOVIVA INC (INVA): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research