6afb5300_usation___HealthNewsReview_org__Study_design
Long-term [acid suppression] therapy, particularly at high doses, is associated with an increased risk of hip fracture Drugs that suppress acids may make fractures more likely Taking proton pump inhibitors for more than a year increased the likelihood of a hip fracture by 44 percent [Problem] Make fractures more likely is causal, as is increased the likelihood; the caveat may does not undo the suggestion of causality [Suggested language] The study showed that people who took proton pump inhibitors for more than a year were 44 percent more likely to have a hip fracture. Such a conclusion would require a randomized trial that includes a control group who didn’t take the drugs. In this observational study some other factor might have increased fractures. That doesnt mean that the statistical link (association) isn’t real; it just means a study like this can’t prove that the drugs were the culprits. [Study design] 
Nested case-control study of the relationship between acid suppression and hip fractures in patients (observational)
Observational Studies - Does The Language Fit The Evidence? - Association Versus Causation - HealthNewsReview.org
Study design