Brian Yoor
Analyst · Evercore
Thanks, Miles. As Scott mentioned earlier, please note that all references to sales growth rates, unless otherwise noted, are on an organic basis, which is consistent with our previous guidance.
Turning to our results. Sales for the third quarter increased 7.8% on an organic basis. Rapid Diagnostics, which was acquired late last year and is therefore not included in our organic sales growth results, achieved sales of $481 million. Exchange had an unfavorable year-over-year impact of 2.7% on third quarter sales. During the quarter, we saw the U.S. dollar strengthened versus several currencies, resulting in a larger unfavorable impact on our results this quarter compared to the expectations had exchange rates held steady since the time of our earnings call in July.
Regarding other aspects of the P&L, the adjusted gross margin ratio was 59.5% of sales, adjusted R&D investment was 7.3% of sales and adjusted SG&A expense is 29.7% of sales.
Turning to our outlook for the full year 2018. We forecast organic sales growth of approximately 7%, at the top end of the guidance range we provided at the beginning of the year. At current rates, we expect exchange would now have a slightly negative impact on full year reported sales.
In addition, we continue to expect Rapid Diagnostics to contribute sales of a little more than $2 billion.
We forecast an adjusted gross margin ratio of around 59.5% of sales, which includes underlying gross margin improvement across our businesses. We forecast adjusted R&D investment of a little less than 7.5% of sales and adjusted SG&A expense of around 30.5% of sales.
Turning to our outlook for the fourth quarter of 2018. We forecast an adjusted EPS of $0.80 to $0.82. We forecast organic sales growth of mid- to high single digits. And at current exchange rates, we'd expect exchange to have a negative impact of a little more than 3% on reported sales.
In addition, we expect Rapid Diagnostics to contribute sales of around $500 million in the fourth quarter, which, as I previously mentioned, is not included in our organic growth rate this year.
Before we open the call for questions, I'll now provide an overview of our fourth quarter organic sales growth outlook by business.
For Established Pharmaceuticals, we forecast mid-single-digit sales growth, which reflects the difficult comparison in our noncore other business segment relative to the fourth quarter of last year when sales increased strong double digits.
In Nutrition, we forecast low- to mid-single-digit sales growth. In Diagnostics, we forecast mid- to high-single-digit sales growth. And in Medical Devices, we forecast high-single-digit sales growth, which reflects double-digit growth in several areas of this business.
With that, we will now open the call for questions.