Aetna Inc. AET is scheduled to report first-quarter results before the opening bell on Apr 28. In the last quarter, this company delivered a 14.17% positive earnings surprise. Let’s see how things are shaping up for this announcement.Factors Influencing this Past QuarterAetna expects its prescription drug plan (PDP) membership to increase over 0.45 million in the first quarter. Membership growth along with business growth should lead to margin expansion.The company also expects its Medicare Advantage membership to increase more than 6% in the to-be-reported quarter with individual Medicare Advantage growing its membership by 10%.Total medical membership is projected at 22.7 million to 22.8 million for the first quarter. This reflects a decline from the 2015 level due to commercial ASC decline of about 0.75 million members and 0.18 million less members in group commercial insured. However, membership growth in government businesses is estimated at about 0.17 million.Broad-based Medicaid business is expected to drive the results of the segment.The company also expects its ACA-compliant businesses to see improved margins in the first quarter.However, the company does not expect any material improvement in individual commercial business. Medical costs may rise in the first quarter. Also, the absence of share buyback may dent the bottom line.With respect to the surprise trend, Aetna surpassed expectations in each of the last four quarters, with an average beat of 13.57%.Earnings WhispersOur proven model does not conclusively show that Aetna will beat the Zacks Consensus Estimate in the first quarter. That is because a stock needs to have both a positive Earnings ESP and a Zacks Rank #1 (Strong Buy) or at least 2 (Buy) or 3 (Hold) for this to happen. But this is not the case here as elaborated below.Zacks ESP: Aetna's Most Accurate estimate is pegged at $2.19 per share, which is below the Zacks Consensus Estimate of $2.22. The Earnings ESP is thus -1.35%.Zacks Rank: Aetna has a Zacks Rank #4 (Sell), which decreases the predictive power of ESP. Moreover, the Sell-rated stocks (#4 or 5) should never be considered going into an earnings announcement.Stocks to ConsiderHere are some companies you may want to consider as these have the right combination of elements to post an earnings beat this quarter: Anthem, Inc. ANTM has an Earnings ESP of +0.30% and a Zacks Rank #2. The company is scheduled to release first-quarter earnings results on Apr 27.AbbVie Inc. ABBV has an Earnings ESP of +1.77% and a Zacks Rank #3. The company is scheduled to release first-quarter earnings results on Apr 28.Amgen Inc. AMGN has an Earnings ESP of +3.52% and a Zacks Rank #3. The company is expected to report first-quarter earnings results on Apr 28.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 AMGEN INC (AMGN): Free Stock Analysis Report AETNA INC-NEW (AET): Free Stock Analysis Report ANTHEM INC (ANTM): Free Stock Analysis Report ABBVIE INC (ABBV): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research