Cost of goods sold and gross margin
Cost of goods sold increased $1.3 million, or 25%, to $6.3 million for the year ended December 31, 2023, compared to the year ended December 31, 2022. This increase was primarily due to higher sales of Barostim.
Gross profit was $33.0 million for the year ended December 31, 2023, an increase of $15.6 million, or 89%, over the year ended December 31, 2022. Gross margin increased to 84% for the year ended December 31, 2023, compared to 78% for the year ended December 31, 2022. Gross margin for the year ended December 31, 2023 was higher due to a decrease in the cost per unit and an increase in the average selling price.
Research and development expenses
R&D expenses increased $1.7 million, or 17%, to $11.6 million for the year ended December 31, 2023, compared to the year ended December 31, 2022. This change was primarily driven by a $1.7 million increase in compensation expenses, mainly as a result of increased headcount and a $0.6 million increase in non-cash stock-based compensation expense, partially offset by a $0.8 million decrease in clinical study expenses.
Selling, general and administrative expenses
SG&A expenses increased $14.5 million, or 29%, to $64.5 million for the year ended December 31, 2023, compared to the year ended December 31, 2022. This change was driven by a $8.6 million increase in compensation expenses, mainly as a result of increased headcount, a $2.3 million increase in marketing and advertising expenses, primarily related to the commercialization of Barostim in the U.S., a $1.8 million increase in non-cash stock-based compensation expense, a $1.5 million increase in travel expenses and a $1.0 million increase in consulting expenses, partially offset by a $0.3 million decrease related to D&O insurance costs and a $0.2 million decrease in professional fees.
Interest expense
Interest expense increased $1.6 million, to $1.8 million for the year ended December 31, 2023, compared to the year ended December 31, 2022. This increase was driven by the interest expense on borrowings under the Loan Agreement entered into on October 31, 2022.
Other income, net
Other income, net was $3.9 million for the year ended December 31, 2023, compared to $1.4 million for the year ended December 31, 2022. This increase was primarily driven by higher interest rates on interest-bearing accounts partially offset by a lower cash balance.
Provision for income taxes
Provision for income taxes was nominal for the years ended December 31, 2023 and 2022.
Liquidity, capital resources and plan of operations
We have incurred significant operating losses and negative cash flows from operations since our inception, and we anticipate that we will incur significant losses for at least the next several years. As of December 31, 2023 and 2022, we had cash and cash equivalents of $90.6 million and $106.2 million, respectively. For the years ended December 31, 2023 and 2022, our net losses were $41.2 million and $41.4 million, respectively. Our net cash used in operating activities for the years ended December 31, 2023 and 2022, was $39.0 million and $42.7 million, respectively.