Inogen Inc. INGN is scheduled to report first-quarter 2016 results on May 9. Last quarter, the company reported earnings of 14 cents per share which beat the Zacks Consensus Estimate by 7 cents.Notably, the company beat the Zacks Consensus Estimate in the last four consecutive quarters, with an average earnings surprise of 31.91%. Let us see how things are shaping up for this announcement.Factors Influencing This QuarterWe believe Inogen’s unique direct-to-customer business model, innovative product portfolio and growing patient base will drive significant top-line growth. Expansion of the company’s direct-to-consumer network and shift to cash sales of systems will boost margins. Meanwhile, new products like the upgraded Inogen One G3 and the upcoming Inogen One G4 are expected to drive growth further.However, anticipated changes in Medicare reimbursements will hurt rental revenues going forward. Moreover, it has been proposed that Medicare patients should take prior authorization for stationary oxygen services. We believe that this will delay the process of issuing new systems on a rental basis, which will eventually hurt the top line.Earnings WhispersOur proven model does not conclusively show that Inogen is likely to beat 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) for this to happen. That is not the case here as you will see below.Zacks ESP: Inogen has a -8.33% ESP. This is because the Most Accurate estimate stands at 11 cents, while the Zacks Consensus Estimate is pegged at 12 cents.Zacks Rank: Inogen carries a Zacks Rank #2, which increases the predictive power of ESP; but when combined with a -8.33% ESP, it makes surprise prediction difficult.We caution against stocks with a Zacks Ranks #4 and 5 (Sell-rated stocks) going into the earnings announcement, especially when the company is seeing negative estimate revisions.Stocks That Warrant a LookHere are some health care stocks that you may want to consider, as our model shows that these have the right combination of elements to post an earnings beat this quarter.Intrexon Corp. XON has an Earnings ESP of +17.39% and a Zacks Rank #1.Quality Systems QSII has an Earnings ESP of +6.25% and a Zacks Rank #2.The Cooper Companies COO has an Earnings ESP of +0.52% and a Zacks Rank #2. 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 QUALITY SYS (QSII): Free Stock Analysis Report INOGEN INC (INGN): Free Stock Analysis Report COOPER COS (COO): Free Stock Analysis Report INTREXON CORP (XON): Free Stock Analysis Report To read this article on Zacks.com click here.