On Jan 18, we issued an updated research report on Quest Diagnostics, Inc. DGX. The stock carries a Zacks Rank #3 (Hold).We are optimistic about Quest Diagnostics’ consistent efforts to refocus on core diagnostic information services business and disciplined capital deployment. Incidentally, the company witnessed significant growth through infectious disease testing, prescription drug monitoring and wellness business.Of late, major developments included the company’s progress in prescription drug monitoring, QuantiFERON and non-invasive prenatal screening. In advanced diagnostics, Quest Diagnostics made a strong improvement with its new center of excellence for precision medicine oncology in Texas. This apart, with the acquisition of Med Fusion, the company has seen accelerated growth in tumor panels.Quest Diagnostics’ latest acquisitions and collaborations with hospitals and integrated delivery networks (the most recent buyouts on the list being US Laboratory Services business of Oxford Immunotec, Provant Health, Hurley Medical Center's outreach operation in Flint, MI) continue to act as major growth drivers.Quest Diagnostics Incorporated Price Quest Diagnostics Incorporated Price | Quest Diagnostics Incorporated QuoteWe are also upbeat about the company entering into a strategic partnership agreement with UnitedHealthcare to join the latter's network for all plan participants from Jan 1, 2019 onward.On the flip side, during third-quarter earnings call, Quest Diagnostics trimmed its full-year revenue guidance to reflect lower-than-expected performance of the metric in 2018. This is primarily due to two factors. First, the company is currently facing headwinds in the areas of prescription drug monitoring, hepatitis C and vitamin D testing.While it has made some progress, the testing areas still affected its revenue growth in the third quarter of 2018. Second, the company saw a rise in patient concessions during the same period, which in turn, hurt its top line. Additionally, the reimbursement scenario persists to be a major cause for concern.Over the past three months, shares of this major commercial laboratory services provider have underperformed its industry. The stock has declined 14.3% compared with the industry’s 7.2% fall.Stocks to ConsiderSome better-ranked stocks in the broader medical space are Veeva Systems VEEV, Amedisys, Inc. AMED and Illumina, Inc. ILMN.Veeva Systems’ long-term earnings growth rate is estimated at 19.5%. The stock flaunts a Zacks Rank #1 (Strong Buy). You can see the complete list of today’s Zacks #1 Rank stocks here.Amedisys’ long-term earnings growth rate is projected at 18.8%. The stock carries a Zacks Rank #2 (Buy).Illumina’s long-term earnings growth rate is expected at 23.4%. The stock has a Zacks Rank of 2.Zacks' Top 10 Stocks for 2019In addition to the stocks discussed above, would you like to know about our 10 finest buy-and-holds for the year?Who wouldn't? Our annual Top 10s have beaten the market with amazing regularity. In 2018, while the market dropped -5.2%, the portfolio scored well into double-digits overall with individual stocks rising as high as +61.5%. And from 2012-2017, while the market boomed +126.3, Zacks' Top 10s reached an even more sensational +181.9%.See Latest Stocks Today >>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 Veeva Systems Inc. (VEEV): Free Stock Analysis Report Illumina, Inc. (ILMN): Free Stock Analysis Report Amedisys, Inc. (AMED): Get Free Report Quest Diagnostics Incorporated (DGX): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research