Fewer patients with obesity used lipid-lowering, cardiovascular, or antidiabetic drugs after bariatric surgery compared with matched patients who did not have surgery for morbid obesity, a population-based cohort study in Sweden and Finland found.

Bariatric surgery patients had a lower probability of receiving a prescription for one of the three categories of medication in all follow-up periods, according to Joonas Kauppila, MD, PhD, of the Karolinska Institute in Stockholm, Sweden, and co-authors.

This included the first year after baseline (OR 0.32, 95% CI 0.31-0.33, P<0.001) and after 10 to 15 years (OR 0.22, 95% CI 0.20-0.24, P<0.001), the researchers reported in JAMA Surgery.

“The use of lipid-lowering, cardiovascular, and antidiabetic medications was markedly reduced during the first years of follow-up after bariatric surgery compared with baseline in the present study,” Kauppila and co-authors wrote. “However, a slow increase in lipid-lowering and cardiovascular medication was observed over time.”

At baseline, 20.3% of bariatric surgery patients and 21.0% of matched no-surgery patients used lipid-lowering medications. After 2 years, the proportion of bariatric surgery patients taking them was 12.9%. After 15 years, it was 17.6%, compared with 44.6% of no-surgery patients.

Similarly, 27.7% of bariatric surgery patients and 27.7% of no-surgery patients used antidiabetic medications at baseline. After 2 years, 10.0% of bariatric surgery patients used them. After 15 years, 23.5% of bariatric surgery patients used antidiabetic medications, compared with 54.2% of no-surgery patients.

However, the proportion of both groups using cardiovascular medication increased over the long term, with a short-term dip in use for bariatric surgery patients. At baseline, 60.2% of bariatric surgery patients and 54.4% of no-surgery patients used cardiovascular medication. This dropped to 43.2% after 2 years for bariatric surgery patients, but rose to 74.6% after 15 years, compared with 83.3% for no-surgery patients after 15 years.

“The results can aid in informed decision-making when considering bariatric surgery for patients with [morbid] obesity and inform patients and professionals about the expected long-term effects of medication use for obesity-related comorbidities,” Kauppila and co-authors wrote.

Long-term reductions in medication use “may infer savings in medication expenses for patients, health care, and society,” they added.

Only two large studies have compared obesity-related medications over time in patients with and without bariatric surgery, the researchers noted. These, they wrote, suggested similar reductions in use, but had smaller sample sizes, shorter follow-up times, did not match controls for medication use, and included patients who didn’t use the medications.

Kauppila and co-authors studied 26,396 bariatric surgery patients and 131,980 controls, using 2005-2020 data in Sweden and 1995-2018 data in Finland. Most patients came from Sweden (77.8%). Bariatric surgery included gastric bypass and sleeve gastrectomies.

Controls were matched 5:1 with bariatric surgery patients for country, age, sex, calendar year, and cardiovascular, lipid-reducing, or antidiabetic medication use. The cohort included 66.4% women and median age was 50. Patients were followed until death or the end of the study period.

Time periods of medication use were measured from the day the drug was dispensed until the number of dispensed daily doses had passed using prescription registry data in Sweden and Finland. The time window expanded if a new dispensation happened within this time period. If a month did not include a portion of that time window, a patient was considered a non-user that month. Status could change numerous times throughout the study period.

In an invited commentary, Paulina Salminen, MD, PhD, of the University of Turku, Finland, and co-authors pointed out that the study “highlights the benefits of mandated databases that report MBS [metabolic bariatric surgery], obesity-related comorbidities, and medications.”

However, Salminen and colleagues noted “several major limitations potentially biasing the results.” The diagnosis code for obesity from the ICD-10, used for the study, “was not commonly used in Finland and even less so in Sweden,” where most of the patients were from, they observed.

They also raised concerns about using the Swedish National Patient Register and the Care Register for Health Care in Finland to identify patients who had bariatric surgery, suggesting that more bariatric surgery patients had been captured by the Scandinavian Obesity Surgery Registry.

The bariatric surgery group was older and had more comorbidities than people in “studies including more detailed and valid data sources,” they noted. The inclusion of weight data could have helped paint a more accurate picture, because “resolution and/or improvement in many obesity-associated comorbidities after MBS is related to weight reduction,” they wrote.

Kauppila and co-authors acknowledged there was no information on obesity treatments or interventions for the non-surgery group. Medication cessation did not mean disease resolution, they added, and differences in severity of obesity and comorbidity between surgery and control groups could have been a confounder.

Other potentially relevant data, like body mass index, smoking, alcohol use, and socioeconomic status were also unavailable.

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