For the 2018 second quarter, practice salaries and benefits expense was $621.0 million, compared to $561.4 million for the prior-year period. Practice salaries and benefits expense as a percentage of net revenue was 67.8 percent for the second quarter of 2018, compared to 66.6 percent for the prior-year period. This increase in expense as a percentage of revenue was primarily attributable to growth in clinician compensation expense at existing practices, support for organic-growth initiatives as well as to support acquisition-related growth.
For the 2018 second quarter, general and administrative expenses were $107.9 million, as compared to $103.0 million for the prior-year period. Included within general and administrative expenses was an increase of approximately $3.2 million of stock-based compensation expense primarily resulting from the change in timing of the Company’s annual equity grant from June to March in order to align the timing with other compensation related activities. General and administrative expenses as a percentage of net revenue was 11.8 percent for the second quarter of 2018, compared to 12.2 percent for the prior-year period.
Earnings before interest, taxes, depreciation and amortization expense (EBITDA) for the 2018 second quarter was $157.7 million, an increase of 6.0 percent compared to $148.7 million for the prior-year period. EBITDA as a percentage of net revenue was 17.2 percent for the second quarter of 2018, compared to 17.6 percent in the prior-year period, with this decline primarily reflecting higher operating expense growth as compared to revenue growth.
Depreciation and amortization expense was $26.5 million for the second quarter of 2018 compared to $25.7 million for the second quarter of 2017, an increase of $0.8 million that primarily related to the amortization of intangible assets from recent acquisitions.
Interest expense was $21.6 million for the second quarter of 2018 compared to $18.5 million for the second quarter of 2017, due primarily to a higher effective interest rate on borrowings between the two periods and slightly higher outstanding borrowings.
MEDNAX generated net income of $79.4 million for the 2018 second quarter, or $0.85 per diluted share based on a weighted average 93.5 million shares outstanding. This compares with net income of $63.7 million, or $0.69 per diluted share, for the 2017 second quarter, based on a weighted average 92.8 million shares outstanding.
The Company’s effective tax rate for the second quarter of 2018 was 27.5 percent, compared to 39.0 percent for the second quarter of 2017, related to the reduction in the corporate tax rate enacted under the Tax Cuts and Jobs Act of 2017.
For the second quarter of 2018, MEDNAX reported Adjusted EPS of $1.07, compared to $0.85 for the second quarter of 2017. Adjusted EPS is defined as diluted net income per common and common equivalent share excludingnon-cash amortization expense and stock-based compensation expense.
For the six months ended June 30, 2018, MEDNAX generated revenue of $1.82 billion, up 8.3 percent from $1.68 billion for the prior-year period. EBITDA for the six months ended June 30, 2018 was $291.2 million, an increase of 3.4 percent compared to $281.7 million for the prior year. MEDNAX earned net income of $142.8 million, or $1.53 per share, through June 30, 2018, based on a weighted average 93.5 million shares outstanding, which compares to net income of $118.4 million, or $1.27 per share, based on a weighted average 93.0 million shares outstanding for the first six months of 2017. For the six months ended June 30, 2018, MEDNAX reported Adjusted EPS of $1.96, compared to $1.60 in the same period of 2017.